I look forward to Winter Field Day as a CARA activity.
Personally, I am happy with the Edgemont Community Centre site if arrangements can be made, probably because it is a 10-minute walk from my house if I don't slip in the snow and fall.
I think that the generator is too clunky without a couple of strong men present. Not sure about upgrading batteries. Good to have batteries available for when generator has to be stopped for refueling. Has CARA ever entered with a full overnight operation?
If I get there, I am personally equipped to do UHF Winlink to the VE6FAR node which I practice regularly. I am set up for using my Yaesu FT-60R handheld, I should be able to connect to the 6-pin data connector on the trailer radio. I would have to make a new jumper board for my SignaLink and figure out the radio menu.
During cold days like the one last year we need heat in a tent. We don't know what weather is coming. One of my thoughts is that last year's winter field day page showed a trappers tent with a wood stove. I don't know if any of these are certified for use in street fairs, etc., but their design must include considerations of fire.
I was disappointed last year that VHF/UHF antennas were not deployed, as that makes it easy to add to the multipliers by looking for the 2-meter Sunday morning net.
I don't have any answers for the rest of your questions at this time.
John