Many thanks to Don McIver for this panel schematic:
Many thanks to Greg Gomes for this information
Square D 30 amp load center. 12/2 wire for 20 amp breaker
and 14/2 wire for 15 amp breaker.
With added ground bar, ground to camper frame is 8 gauge.
Neutral (white) to neutral bar that comes with load center,
all grounds must be kept apart from neutrals and are grounded
to the added ground bar (left) on load center.
10/2 wire run to junction box under bed. 20 amp extension
cord from box to campground. 20 amp GFCI. 10/2 wire could
support 30 amp if desired.
12 volt under front seat, battery is in a home built box vented
to the outside and will have a sealed lid.
The vent is a 1/4" plastic tube, well a modified P-Trap that runs out the bottom of the floor with a screen in it.
Showing my ground coming from the box to the frame by way
of a hole I drilled through the floor. The other holes you see
were to access the axle bolts.