I am lucky that DH is a pastor at our church, which happens to be really really close and he has keys. We go to the church and push tables together and SPRAY baste!
I used to do it on the floor. You can do it in sections on a dining room table. I know people that use an old ping pong table, those are pretty good sized.
Maybe you would want to invest in a pair of adjustable tables from Costco or something that you could store in the garage(folded up) and move to the driveway when needed.
The plywood on the bed sounds like a good idea.