I added a separate 30A circuit to power an additional electric skillets/toaster and future 2nd A/C... I also added an inverter w/extra outlets & moved some of the original outlets around. When doing so I found that the original wiring was a hot mess with many wires going diagonal with no extra slack.
Therefore, if you are moving an outlet at the end of a circuit closer to the direction of the supply line, then you don't need to rewire it, you'll actually create slack during the move. However, if the outlet is in the middle of the circuit and/or you are moving it away from the source, don't count on there being any extra slack.
I just used some left-over household Romex wiring rated at 15A & it appeared to be better wiring than used by the manufacturer. Also, the outlet boxes & outlets I installed were much better quality. IMO they use the cheapest wiring/boxes/plugs that code will allow...
2011 RAM 2500 ST Crew Cab 5.7 Hemi
2011 Primetime 3150BHD Touring Edition
Days camped in 2016-36
Days camped in 2015-37
; Days camped in 2014-31