I backpacked with a 4X5 Sinar system and a dozen sheet film holders for 20 years.
I also now use 12 Toyo double holders (one of the heaviest types). Don't think I'd want to go with any more than that. I hear Peter Dombrovskis used to go out on his trips with 20, but they had to last him for days/weeks at a time. Apparently he only ever shot a single exposure of any scene as a result.
