Barry - you and your vet are right, overly long nails can lead to problems too.
However, I leave Dugan's nail only slightly longer in winter. In non-winter, I keep them trimmed such that the claws do not contact the surface he's walking on (no clicking on wood floors). In winter, they're maybe 1/16 to 1/8" longer, slightly above or even with the pad. Long enough to click, but short enough that he still has to dig in hard to get a benefit from them. As for a stickier surface on a bootie, the only thing I've ever seen that helps on ice are bare paws and claws. If we hit an icy pitch, he strains, leaving scratch marks in his tracks, but makes it. My last dog once started sliding down an icy stretch that we were attempting to ascend - bad enough that I was crawling - as he was sliding he planted all four feet, dug in with his toes and came to a stop. You could see from his tracks that his nails were what enabled him to stop the slide.
Yes, packs can make a good outer layer for a dog. Looks a little more "hikerish" than a coat!
As for sharing a sleeping bag, I've never winter camped with a dog with a sparse enough coat to require extra insulation. I carry a closed cell foam pad for the dog. It also helps to protect the tent floor from dog feet. A big furry dog can also help keep a tent 10-20 degrees warmer than I can alone. Of course, then there's the dog breath condensation factor....