I just ordered a 35' length of 6/4 "SOOW 600V" flexible cable from Wire and Cable to go. It's pricey for sure, $3.25 a foot but from my research on here (on another RV Net thread) "6/4 SOOW" is supposed to be very flexible down to minus ten degrees or something like that. I already know "cheap" wire is stiff so I'm going to try this stuff. I'm a believer in "you get what you pay for". We'll see. The 50 amp cable that came with our rig is stiffer than a board even in the summer, up until this season I've been using a 30 amp cord with an adapter for the same reasons most everybody else is
I'll try to remember to update on how and what this stuff is really like. It doesn't come with ends but I'll get my own and attach them myself. Should be here in a few days.
Dan