I spray baste my larger quilts on my bed. I have trouble with my back so spraying on the floor/ground does not work for me. I remove my duvet and cover the bed with a clean, old drop cloth. Then I cover that with another thick cloth. I lay my backing down and smooth it out and use T-pins to secure it tautly (is that word?). Then I lay the batting down. I then roll back half of the batting and spray. Smooth it down, then roll the top half back and spray then smooth that part down. I let that sit for a few minutes then I repeat with the top. All of the layers are well adhered and wrinkle free.
I use 505 exclusively. I do not have a problem with overspray at all. I do open a window (if it is a windless day). I think that the problems with overspray come in from being too far away from the object. Also, I make sure that I have a decent sized border of protective covering under the quilt. I would definitely suggest you try it on a bed. It is so much easier. I am actually looking for a nice large piece of fleece backed vinyl to use. Then I would only have to cover with that layer rather than the two.