In general, I don't think it would be a good idea. Most speakerS like being away from walls so an enclosure would not be a good thing. Also, I am pretty sure the RF-7 is a rear ported design so that could cause some really bad bass effects. If you have to enclose them, I would look for a sealed enclosure or front ported speakers. Again, I would not enclose them at all, but front ported would probably minimize the bad effects, although not completely.
Also, there are speaker companies out there that make larger inwall speakers that are designed to be enclsoed. Legacy Audio comes to mind. Although a bit on the expensive side. These are not your typical in-walls.
SHinerman