On generators, I like the sliding bar which makes it impossible to both have the gen on and the main breaker on.

SIDE NOTES:  When I mentioned UPS's, I did mention their best suited to giving you time to shut down. HOWEVER, if on is inclined, the battery can be tapped for adding, in parallel, additional batteries, like you'd have in your camp trailer, to give you more run time.

One of the neatest "generators" I've seen took a lesson from grand father and coo coo clocks:  A small railway track was made on a hill of a property.  On it was placed a cart filled with rocks or concrete (back up carts could be  used too).

When power was on, the cart(s) was/were pulled to the top of the hill and parked there. When power was out, each cart was freed, one after the other. They would move down the hill slowly. VERY SLOWLY. As they moved, they turned a flywheel and generated power.

Geared properly, it could take on a week to get down the hill.  They could be pulled back up via a motor, when the power was on, or a horse could pull them up using a block-and-tackle.