I am testing out a heavy duty tarp on my A128S.
I bought a "silver" tarp from Harbor Freight for $20.
I think it was this one:
Reflective Silver Tarp - 15 ft. 2'' x 19 ft. 6''
It seems to be a good fit. I placed terry cloth towels over the bubbles. So far so good we just went throught several 100+ degree days here in Alabama.
My goal was to try and protect the camper from both rain and sun.
I'll let you know how things work out.