It should be fine. I have never had issues using coloured stuff. i have used printed stuff as well and not had issues.
If your rabbit is eating it, then it could be an issue. It is plastic after all. Just protect the edges from being chewed and you should limit most problems.
I slide them over the edge of the sides. Poster hangers are used to hang up posters. They are 2ft long and come in packs of 2. You will find them with the posters in stores like Walmart or HMV. They are about $3 a set.
Here you can see it along the bottom (I don't have a better picture at the moment).