I think it's a good idea. I think I might do this too with the new bunnies. My existing two are indoor rabbits but we don't have a garden at the moment (but are moving soon). We are getting another pair and I think this would be a good set-up for them, esp as I will have to keep them separate from my other two. But I would never leave them out at night as scared of foxes. Also they will get more fuss and attention if we have them indoors!