Anyone with personal experience anytime between mid-November to mid-December? I'd like to give it a go, but with the shuttle complications i'm looking for some assurance that we'll make it forward one-way without frostbite/hypothermia issues
If the canyon is dry, it shouldn't be a problem, but if it is wet and requires much wading and swimming, carrying "some neoprene socks and otherwise just carrying regular gear" is asking for trouble (also, lower Buckskin always has some wading regardless, usually knee deep).
Unfortunately, there is no way to predict conditions this far in advance.
Here is a trip report from a February trip through the Buckskin:http://climb-utah.com/Escalante/buckskinice.htm
Conditions such as this aren't that unusal December through February.
Keep in mind that the Buckskin will never see sun that time of year, so weather averages for the "above ground places" won't do you any good.
Mid-November is going to be much better than mid December. Either way, if you do try it and take only "some neoprene socks and otherwise just carrying regular gear", you can still try, but I'd highly suggest turning back if you reach water. If you want a better chance of completing the route, and don't have a reliable update on conditions (i.e. someone who's actually been through just before your trip), take full sized and thick wetsuits/drysuits as well as proper footwear (i.e. 5.10 Canyoneers or equivalent).