I used fusible batting using two folding tables. sometimes i pin baste around borders and in the quilt a bit for handling while quilting on machine. if spray basting i too do it top and wait and then backing. or vice versa. I do that on folding tables too.
tried outside but wind is not helpful. but i use 505 spray. good stuff. tried a different brand and it went everywhere i didn't want it to go. wasteful and a mess. 505 goes where it is aimed.
since i quilt slowly, removing pins as I go isn't a problem for me.