Let me start with a link to show you how ambient light can mess with a projected image. Unfortunately, it's not your room and was shot after dark, so I'm using lights in the room, but you want to know how ambient light messes with a projected image.
http://www.avintegrated.com/lighting.html
Now, I am down with front projection in a family room, but any ambient light is going to negatively impact what is on screen, and you will have to suck up the loss in quality. The fact that you have those speakers in that particular room indicates to me that you have some serious addiction problems already. (ha!) So, you will have to balance your need for image quality against the desire for perfection.
With the speakers where they are, and your setup, you really are in a motorized acoustically transparent screen situation it seems to me. Your ceiling is tough, and I would probably look to build a soffit in front of the speaker area which you can mount a screen behind (or in) to hide it, and have the screen drop down in front of your existing speaker system. I like that the area where the screen will be is reasonably dark without any direct light falling on that wall, but obviously, any ambient light will impact things, and the white walls and CEILING are especially bad in the projector world. Any chance to add some darker colors to that room?
From there, a projector like the Sony HW45ES still delivers about the best image available under $2,000 on the market. From there, a JVC RS420 or RS440 is an incredibly good way to go. Maybe get one of those for under $3,000.
No, I don't see a way to avoid an AT screen with the way things are setup.
Moving the screen forward a bit will allow you to get to a 120" diagonal for a bit more reasonable of a cost. But, you want a tab-tensioned screen, and those will run you about $2,000 at the very least for a quality model from DaLite or Draper. Yes, tab-tensioned, yes, acoustically transparent for best results.
Short throw, as you already found out, demands a perfectly flat screen, which causes issues when the screen is retractable.
In my world, I get rid of all the gear up front, move the subs out of the line of site, or leave them just under the screen, go to a flat center channel, and put the main L/R speakers on either side of the screen area. Put the motorized screen on the front wall into a soffit and have it drop down about 5" or so off the wall and put a 85" flat panel TV on the front wall so you get top-shelf daytime viewing with lights on or off, then press a button on the remote and switch to the projector and 133" of diagonal for movie night.
