Sheet metal has won out, as continuation of the existing roof. Will last most of forever, matches everything already on the property and will provide an almost 4' wide sheltered walk for when I'm out filling feed buckets or usingf the second freezer.
What I can't bring myself to do, however, is spend $50 for a piece of concrete board just to put it in the bottom of part of their cage to give them a solid surface to wear their little nails on. But any wood I use will be swollen with rot and falling apart in months. Considering using
porcelain tiles or similar. durable, but lower weight. Four of those would fill one corner of the cage, 22" x 30", provide a spot for a bunny hut.