the platform edges can be taller, since they can form a tray around the mattress without affecting the height of the mattress top.
the bed will be lifted the the ceiling when not in use, so keeping the platform as thin as possible is a high-level goal. The alternative is to use 80/20 stuff for the whole platform. I'm weighing the pros/cons of building a single-piece 60'x75' bed platform using these as a starting point, probably with 80/20 1020 beams (positioned on edge) along all 4 platform edges.
I'll make a trip to the local outlet to check it out myself if no one knows, but does anyone happen to have the true dimensions of those three panels? by which i mean thickness, end-to-end length (not including the hooks etc at the top end), and rung-to-rung spacing? I know several folks have used this ATV ramp from H-F as a basis for their bed platforms:
