My local Hardware store either Lowes or Home Depot has THHN cable. A bit stiffer, but available right away. Otherwise its Amazon or Wireandcableyourway.com.
That’s quite the run of wire for a camper. Are you putting this in any kind of conduit or split loom?
I'm adding a 400ah lithium pack and want to have it in the rear storage area instead of up on the tongue of the trailer. I also don't want to do to much hackery to the factory wiring.
The frame has a set of holes through it. It will be loomed and run through grommets
I just purchased some Ancor 2/0 wire, if you want some tinned and fine-strand wire that’s your best bet! If you want great wire fine strand and bare copper get some welding cable.
Any larger I like fine strand since it will help with flexibility