Generator prep is for onboard generators, too much $$$ to just store a portable generator in it since portable generators are not designed to operate in such a confined space. Since you don't plan much camping off the power grid, a portable will suit your needs better than the expense and maintenance of an onboard genny.
A 2000 watt inverter genny will run most items including most microwaves where a 3000 watt or higher inverter genny is needed to run most AC units. Nothing wrong with having the generator prep done by the manufacture as they tend to do the best job. Who knows, you may change your mind and add an onboard later down the road. Either way it should add to the resale value.