Plumbing is pretty easy to follow by opening cabinets, looking behind drawers & in access hatches. The routing of wiring is not... Yet, you can determine the start & end points pretty easily with the 12V by turning everything on, then pulling fuses one by one.
110V can be done similarly with the breakers. If necessary, (TURN OFF THE POWER FIRST) you can dismantle the 110V receptacles if they are routed with more than one romex, then ensuring things aren't shorted together, turn on the power again. You can test for receptacles & other objects to see if the power remains.
I found the receptacle over the sink was wired to the one beside the entertainment center this way, and those are wired to the microwave circuit.
Have fun! (and be safe)
Formerly: 2000 Four Winds 26Q/Ford, '96 Kit Sportsmaster 22' 5th wheel, '91 Sunlite truck camper, Wildernest flip-top canopy