We are doing something similar but a bit more basic. We purchased some
canvas from a surplus stire, a gromit kit, some tent poles and guy lines,
and some clamps. Cut ans sew the canvas to size, hem the sides, place
gromits at the corners, treat the canvas, then clamp one side to the rain
cutter and use the poles at the corners. Should work although it will be
prone to the moisture sag Stephen mentioned.

Thanks,

Jeff
90' Carat (It's Blue, It's Beautiful. Now sporting a very unstylish brown
interior taken from the parts bus)
86' (We call this one Parts)
85' GL (Sidelined and feeling neglected)