Dry ice would work, but is it readily available? Expensive? The local meat plant uses dry ice, but they don't sell it to the public. Search "dry ice" or CO2. Here's an interesting link with some practical info: http://www.granthagbergco.com/dryice.html
A cubic foot of dry ice weighs 50+ pounds, and should last 4 to 5 days.
Storing a fresh pelt with regular (frozen H2O) ice in an ice chest, would be similar to storing it in the fridge. I've kept pelts in the refrigerator for 2 or 3 days with no problems. That would be ok for a weekend trip. I really don't know long you could keep a pelt on ice before it spoils? It would be similar to keeping a piece of fresh meat, if you'd keep it buried in the ice and the lid closed, a week would be pushing its lifespan. Warm weather, opening and closing the lid, the original condition of the pelt, etc. will all affect it's lifespan and lessen it's value. So that's not going to work, for 2 weeks anyway.
Another option would be a propane gas freezer. Search "propane freezer". That would make a guy's outfit "self-contained", but they're expensive. Otherwise we're going to be tied to an outlet. Or a small power-unit.
Above I listed a tarp and plastic bags, it would be good to have a big sheet of plastic too. If a guy is forced to skin outside in bad weather, you can always find a tree where you could fashion a lean-too, with a rope and a couple trap stakes. Personally, I don't think it would be practical to figure on fleshing/drying pelts while I'm out of state. If I go for fox, and take stretchers, tools for them, and the place is loaded with mink and/or beaver, what am I going to do with their hides? How many stretchers do I need? Without an 18-wheeler, you just can't take everything. It comes down to having access to a freezer.
We need to talk about washing, cleaning, after handling these animals too.