Buddy,
The RV electrical devices are self contained, so they don't need a box. I have never found them, and actually don't like they way they splice into the wire. I just used "shallow" cut-in boxes from Home Depot. It gets tight in there, but they work if you use the side screws instead of the push in terminals (Most force you to anyway with 12-gauge wire because the push in holes are gauged to 14). For the basement, you could even surface mount, or go to the ceiling like Keystone did.
Good luck, and add a battery operated smoke detector to the basement while your down there! (my community service part
in lieu of standing on the corner with the fire boot this year)