Enclosing the underbelly: a few design questions

Good point, Larry! So if I understand it correctly, with your method, the aluminum support rails can go essentially anywhere, since the beam clamps can slide up and down the web on the frame members?

And when you say "bolt the panels together," do you mean the foam panels with the coroplast covers? Or do you use an "underskin" of aluminum sheeting?

Thanks again for all of these tips!