Probably an RV Tech or RV shop that has experience in modifications.
The toilet 12v should not be a problem, just tap into a nearby 12volt line, no special boxes, wiring protection.
The ceiling fan, 120 volt, slightly different story, Power could be obtained by tapping into a 120 receptacle in the bedroom, but concealing (protecting) the wiring up to the location in the ceiling would be much harder, you may have to use a surface mounted wire chase.
The bigger issue would be mounting the 120 v, octagonal electrical box (required to mount a residential ceiling fan), to the RV ceiling would be the biggest problem. A residential electrician, unless he is an RVer, probably wouldn't have a clue on RV construction
Ken