SOP for me in winter. I second all the advice that has already been offered. If you want more security, use two per wing- one each forward and aft from each strut. I use one on the tail as well. They will pressure-thaw, but not drastically or catastrophically. More of an issue if you are hanging from one at a belay on an ice climb during a really, really slow pitch, or during load-hauling or high-angle rescue. Piling snow on top definitely inhibits solar melting. Be sure to have a shovel to dig them out, but of course you have one in your plane in winter anyway, right? Last advice- Be sure to bang the ice out of them as soon as you remove them, or they will be clogged and useless until the next thawing opportunity. To do this, hold them upside down and beat the hanger (the eye) on hard ice until the ice core inside the screw falls out. Oh- and it is not the angle of the placement that creates holding power, it is the threads themselves. So place them directly in line with the pull, instead of tilting away. A lot depends on the integrity of the ice. For the guy that carries them on the sno-go: They work as well or better in frozen moss or tundra, if you can't get good ice.
Wire gate biners such as Black Diamond Hotwires or Livewires are a good bet in winter- the gate on them doesn't freeze in place like a solid aluminum gate tends to do.
V-threads are legit. Mostly used where you need to rap off a climb and can't go back to break down your anchor and get your screws back, or, if you're running low on screws. If you have a few anyway, it's generally faster and easier just to place 'em, and clean 'em when you go. Freezing almost any kind of random dunnage to the ground works fine, if you don't mind leaving junk behind when you leave.