I use 505 spray for my basting.
One tip, spray the cotton not the batting. Batting will soak it up, you don't have to use much, just a light mist on the cotton and slap that batting in place.
I lay out my backing (right side down), spray lightly, place the batting on and smooth it out.
Then I lay my top face down, spray the back lightly, and place the already stuck together batting and batting on top of that and smooth.
I don't have the floor room so for larger quilts I go to the quilt shop and use their tables in the back room, they allow us to do that and its big enough to spray and smooth without difficulties.