Are you asking because you want to land somewhere and do some serious skiing, or just because you want a contingency when you become stuck?
If it's the former, electricsnail sounds like the man to talk to. If it's the latter, here's my 2 cents: No reason you can't fly in nordic ski boots, especially if you're on straight skis and have no toe brakes anyway. Alternately, a number of people in my area have plastic free-heel bindings that accept any style of winter boot. You won't see these in Warren Miller movies, but friends of mine have done winter circumnavigations of Denali using them. Try your local Army-Navy store. Screw them to a pair of yard sale skis and you're there.
With due respect to Paul and his considerable experience and judgement, the Talkeetna pilots I know (Jay Hudson, in particular) favor snowshoes for packing runways, because of more effective compaction. I have packed runways using both skis and snowshoes, and I agree that for packing runways, snowshoes are far more effective in deep powder. In terms of travel and covering miles to get back to civilization, skis are often going to be more efficient, assuming you have the skill to navigate the terrain, and not hurt yourself in the process.
If you don't have extended baggage, and don't want to do anything dodgy with respect to aircraft loading, then look for wider, shorter skis. The net area of the base is what gives you floatation.
FWIW, -DP
p.s. Skis are like airplanes- One setup that does everything you want optimally is pretty much of a myth. If you could, how many different airplanes would you want to have access to? At last count I had about 14 pairs of skis, but unfortunately, still just one airplane...
