Tape is a good idea.
Use that blue tape made by 3M.
It is light tack and won't peel off your new finish.
Pre drill with an 1/8" bit to mark the spot on the back of the door and then drill with the right size bit but only 1/2 way from each side. Making a template is a good idea. If you are using a paper one or just measuring, an automatic center punch is helpful. Bosch is a good brand of drill bit available at HD.
Why don't you hire a carpenter so that you can have somebody fresh to reem out on this new day?
j/k
... kind of ...
It's the other kind of 'drilling' where pushing hard gets favorable results. Don't approach this like you're taking the field. I know it's early but it is Sunday so a couple of 'relaxation' drinks might be in order to set a nice calm tone for this labor of love.