I'm working on my 40 gallon vertical conversion and making the background using Great Stuff foam (pond and stone kind). Unfortunately, I pinched the sciatic nerve in my back and now can't lift or move the heavy tank. Is it possible to spray on the Great Stuff foam while the tank is in its upright position? The photo tutorials I've seen all have the tank laid on its back. Will the foam run down if I spray on a vertical surface?

I don't want to risk messing up the background, but it also could be several months before I'm able to move the tank again. Does anyone have experience using Great Stuff on a vertical surface or am I just going to have to keep my guys in their quarantine tanks until my back heals up?