I've got a number of friends in the film business (well, they were in the film business, but that's nearly dead here now) and I've assembled a fair amount of gear over the years, including 100 feet of 200A banded cable with Camlock connectors and a set of very well-made clips that allow me to tie in directly to any breaker box. The clips consist of self-adjusting vice-grips that are sheathed in heavy copper, with heavy rubber insulators that slide over them after clipping in... the idea is, you clip them directly to the bus bars in any breaker box and they supply you with up to 200A of 240VAC. Their weight is supported with short lengths of cord that are tied to small clamps mounted at the top of the breaker box. It's slightly risky but if you know what you're doing, it's a piece of cake. It struck me today, with a proper connector in a box with Camlock connectors, I could charge my Tesla (arriving in about 2-3 weeks) at 30A anywhere I could access a breaker box, with a small kit in the trunk and a screwdriver! Or, perhaps I could make a portable box for 70A service, once I find out what's inside the 70A box.