I think you just mean the address on the forms. Just look up a condo somewhere and put that down. They will only check this kind of thing if you apply in country because it’s not reasonable to ask for a rental agreement or something for a place you haven’t even been to yet.
Note that you will have a much easier time opening a Thai bank account with a one year OA visa than an entry stamp and you will need one so it should be one of the first things you do. Choose a branch that you expect to be convenient to visit in the future since that will happen eventually.
Some of the single entry TR visa requirements seem a bit strict, like needing to prebook your accommodation while in Thailand. Do they not enforce that one or something?
Also make sure to go early because it could take awhile. and let someone know what you are doing because while they probably won’t arrest you, they could.