Pictures are worth a thousand words.
Thanks mpact for the picture and designs, it is worth many useless words.
I see now exactly what is your situation. But I cannot resist a short comment: such nice speakers in a tough situation.
But, let's see what we can do for best compromise.
The #2 option, just let's forget about it, it's just not practical enough for you.
And I can put myself in your situation, so I'll work with you on the best compromise.
The #1 option will be the one that we'll be working with.
If I remember well, the ports on your Studio 20s are in the front, right?
Or are they in the back? Because if they are in the back, you want them some distance from the front wall for sure. And even if they will be on the front, the same principle apply.
Now, you definitively want some speaker's stands.
You can find some very sturdy ones, without spending too much money.
Now, look for 28 or 29" high speaker's stand. I do agree with you. You want a strong and large enough top plate for your speakers, and you want a good speaker stand, not a cheap frail looking one that can tip your speaker easily.
So, you should be able to find one at 28" height with a good sturdy base and post, plus a large enough top plate.
After you find the perfect speaker's stands (don't be cheap to invest a reasonable sum for good stands, I'm sure that you can get some for less than $200, or even $150 or so), you can put some blu tack on the top plate and add another larger top plate of about an inch or so thick. So, in the end it will be perfectly fine.
Now, from your plan #1 drawing, I will get the left speaker about 3 to 4 inches closer to that left wall. And the right speaker, about 2 to 3 inches more to the right.
Now, both speakers will be about 2 and 1/2 feet from the front wall, and if you can go with 2 and 1/4 feet, that will be excellent. So from what I can see in your design, they will be close to the shelfs on your front wall. No problem with that, go for it, just closed to the shelfs if it's possibly practical for you. You'll end up with the front baffles of your Studio 20s at approximatively 3 feet from the front wall.
And if you can move your desk about 3 inches or 4 to the right, that will be great (3" will do just fine), if it's still possibly practical enough for you. If not, just a couple inches (2") will do it too.
Ok, that's it. I believe to be one of the best compromise that you can make right now in that room with these dimensions for all practical purpose.
As for the distance from the speakers to your chair, that's the easiest part, you just have to listen to some nice recordings with good imaging, like Jennifer Warnes "Famous Blue Raincoat" and try various distances till her voice his dead in the center with good separation of all the other musicians playing with her. Just put your desk at the side for this test. And when you found the sound that gel very good at your sitting position, just repositioned your desk in front of your sitting position. My best guess is that your ears will be at approximatively 9 feet from the front wall, which means that your desk will move a little more closer to the front wall.
* Can you see a smart pattern in my recommendation? Indeed, I am using a proven formula on listener and speaker's positioning, the 1/5th formula.
Your room is 15 feet long (deep), your speaker's front baffles as to be as close to the 3 feet positioning from the front wall, which is 1/5th from the total room length.
Your listening position (your ears) have to be at about as close to possible of 9 feet from the front wall, which is 3/5th of the total room length.
And finally, your room is about 10 feet wide (or more like 11 to me).
So for the width, I'm using the 1/9th formula, another good proven positioning method. And I'm using the 11 feet width of your room. I took some liberty here, but you can easily adjust that, now that you know how to calculate (1/9th of 10 feet is about 1.12 feet).
* [Just remember that important point: always measure from the center of the tweeter to any wall. And measure from the center of your ears too.]
Your left speaker tweeter, I want it at about 1.222 feet from the left wall, which is 1/9th of your room (11 feet) width (I wanted to use the 1/7th formula, but with your room, computer desk, front door entrance, and other related aspects, I choose instead the 1/9th formula; you do have to compromise sometimes for your best overall benefit).
And your right speaker tweeter, I want it to be at about 3.666 feet from the right wall, which is 3/9th of your room width.
That's it. Done. Now you got the magic formula at your disposition.
And you also know which speaker's stands to get. And how to adjust them perfectly for you, because you have to know that your ears can be between the tweeter and the woofer height of your speakers, and you will be in excellent shape. And when you work at your cvomputer, you always bend a little bit down too, or you just lay back in your chair to relax with your body lower than usually. So what this means finally, is that with any speaker's stands between 26" and 28" high, you'll be perfectly fine. So, rejoice, indeed.

And like I previously said, a speaker stand is easily modifiable by adding an extra top plate to it very securely with blu tack, without damaging it, and without loosing any audio benefits.
I will even add that even if you find a 26" high speaker's stands, you'll be able to eventually use them too on different heights from different type of seats. Your studio 20s are 15" high, the stands are (supposedly) 26" high; so the top of your speakers (after some spikes or some rubbers under the base plate) will be at about 42" from the floor (I will even say 42.5 inches).
Now, the tweeter on your Studio 20s are quite high on the baffles.
So, that means that you can be as low (your ears) as 36" from the floor, and if you add a nice thick plate of 8" (W) by 12" (D) by 2" (H) made of some hard wood or even marble, your ears can be as high as 45 inches.
Recap for stands:
1. 26" high stands = approximate ears listening height, from 35" to 45".
2. 28" high stands = approximate ears listening height, from 37" to 47".
These wide variations are possible due to the flexibility of adjustments from under the base plate (up or down) to the top plate easily increasable height by adding another top plate on top of the original one.
Ok, I'm done with this post now. If you have further questions, don't hesitate.
Regards,
Bob