I reread your original post. I may not have answered your question. The question is overly general. The best place to power your camper when setup for occupancy is through the shore power cord to a 30 amp 120 volt or 50 amp 240 volt service supply. (Which ever you have.)
This will provide 120 volts to your AC, Micro, and water heater. It will also provide power to your WFCO converter/charger which will provide 12 volts to lights and such as well as charge your battery.
You can also plug the shore power cord into an external generator.
A 20 amp 120 volt outlet from a nearby building can be enough for limited use of your 120 volt appliances. It will be fine for charging your battery and powering your 12 volt appliances.
Generally, your tow vehicle or a solar panel is the only external source of 12 volt power you would want. Neither will power your AC, Micro, or water heater.
There are of course endless options and custom solutions, but they require much technical knowledge. It can be a great hobby to develop.
I wish you happy trails ahead!