Thanks, folks, for the useful info.
I haven't bought an ebike yet. I have a deposit in for a new trailer, though, and an inverter is one of the options on the build sheet. I can also have an outside outlet to charge that li-ion batt outside the trailer... maybe in a fire retardant bag. Like I said, I'm thinking ahead.
Glad to have confirmation that my idea isn't crazy or that I was missing something important.
I toyed briefly with the idea of a dual sport motorbike, but I've never been a motorcycle rider, I'd probably need to trade the SUV for a pickup, upgrade the DL, tag and insure the thing, and motorbikes sound annoying to me anyway. A fat tire e-bike with suspension will be much simpler to deal with all the way around.