Yeah, in situations like this (10 hours of charging, only household outlets), I've been known to do either of two things. I built myself a "Quick 220" device (with relays, for shock prevention) to allow me to charge from two household sockets that are on different phases. That might just get 100 miles in 10 hours. Or, I always carry around with me my own 50A breaker that I can plop into a breaker panel, attached to a length of 50A SOOW cable ending in a NEMA 14-50 receptacle. Voila, instant and temporary 14-50. Of course, you do have to remove the panel face, and leave it off while charging, so don't do this with any small children around. But then again, I'm kinda extreme