FYI: Spray foam needs air to expand. Inside the closed enviroment of a items such as a 2"x2" hollow tube (even one with extra holes drilled into to allow the foam to expand), the foam will not expand except within the first inch or so (often less) of the tube opening. We know this from personal experience. We did not foam the frame tubes of the Blue Bird.
scroll down to find "tips on what I use to cut foam" if you yourself will be cutting the foam down flush.