If Arve's suggestion of using symlinks to manage the encapsulation amounts to your second suggestion, I concur that sounds like the simplest approach. It's our job to see that the RESTXQ paths don't overlap in any case isn't it? :-)
True, symbolic links can be used, too (at least, I guess, on Linux & Unix-based systems; you may have to try and see what happens). I’m not 100% sure what you are after here.. What’s the main reasons for not leaving all RESTXQ files in the restxq (sub)directories?