Mark B,
Your best bet is to take the advice of time2roll. Do the unit up as any good modern (pick a good name here) manufacturer might do on their top of the line units. Chinook was that at the time. (I remember them.)
Set it up for 30amp source (unless you really want to go with 50amp). Use a dis-connectable 30amp shore cable. Find a good hiding place for the PD4045 and go to it.
If you do all of the internal with marine grade wire, it will not even cost 10% more and the flexibility of the stranded wire will make everything easier. The only downside is that you will have to actually wire the devices (like receptacles and switches) because you can't use the marine wire in the push in devices, that wire has to go under a screwed down binder. Marine wire is both tinned (for corrosion) and stranded for both flexibility and fatigue resistance. Hopefully corrosion will not be an issue, but the other will be.
You need to do some thinking now. Set up for at least two spare circuits on both sides (12 & 120) and when you are done, you will probably wish you had more. You did not say how long the unit is, and Chinook built a lot.
You will want at least one AC circuit for each 8 feet of length with a pair of duplex on each, at least a single duplex for the galley and one dedicated for the Air Conditioner - that should only need to be 15 amp. That might want to be 12AWG, but the rest need only be 14. Have you thought about installing a roof unit? If you do, either get a heat pump unit or one with a heat strip in it.
There should be a least 2 circuits for the interior 12V lighting. You will want a dedicated circuit for the potable pump and another if the heating furnace is fan forced, that should have its own. While you are at it, put some DC mouseholes (like lighter sockets) in strategic places to us car chargers for phones and tablets.
I know I have covered a lot here, but prior to the depression, I did a lot of power upgrades in both old RVs and performance cruisers (those are what retired racing sloops become).
If I have lost you and/or started more questions, I am here a lot. I am happy to answer questions and give explanations where needed. I have learned a lot in my years and a lot of that was because the folks that did know this stuff were willing to share it with the kid (then), and I am doing my best to pay that back.
Matt
Matt & Mary Colie
A sailor, his bride and their black dogs (one dear dog is waiting for us at the bridge) going to see some dry places that have Geocaches in a coach made the year we married.