As for the ramp, someone asked about that recently. If you scroll down to TheSnufflenoses it explains my experience with ramps. In summary, I had 1 ramp they NEVER used, and when I made a new one they immediately LOVED it and ever since then they run up and down it constantly with great ease.
I used a thin wooden board, sanded well all over and at the edges, a pure cotton rug (or fleece would work too), velcro strips to attach the two, and zipties to attach the ramp to the top story. You'll need to get someone to drill two holes in the wood at the top of the ramp to put the zipties though.
As for a choroplast ramp, using only 1 sheet of it simply was NOT stable enough (even for our young pigs). If you do make it out of choroplast, be sure to double up on the sheets/attach them so they are extra stable and also be sure to cover the top/ramp part of it in fleece or a rug (be sure the material is safe for them though). Good luck!
Ramp thread:
http://www.guineapigcages.com/forum/...tml#post295538