I saw that Wiggys hammock bag too! Some guy named "Shug" who is a considered an internet expert by all the hammock folks is pretty much using and praising his own DIY version of the Wiggys hammock bag so it isn't that ludicrous or new and idea. I dunno how that thing keeps the bottom tight to your underside though.
If I were to do the UQ thing again, I'd go with 3/4 length for everything regardless of temp and subtract at least 15°F of temp rating from anything that is advertised. I would get Climashield Apex for eveyrthing. That is a personal thing but this is what I have found to be true for me. The full length UQ need bungees closer to the center also to keep the area under your butt from drooping.
I had once been hanging by a creek at near freezing, 100% humidity and EVERYTHING got wet and coated with ice though no rain ever touched anything. I don't want to rely on iced up goose feathers.
Specifically, I would get one these at the "corrected temp rating" of your choice: http://www.arrowhead-equipment.com/store/p312/Jarbidge_River_UnderQuilt.html
No matter what, the lower the temp rating of the full-length UQ, the heavier it will be and the more likely it will dr0op near the middle unless it has extra bungees. Full-length UQ also suffer droop around the bend behind your legs and create an open cavity for cold air to intrude. This has been addressed by modifications called the "stretch mod" or "knotty mod". These are not problems with 3/4 length UQ's.
For my feet, I use a Kifaru Doobie Express as an elephant foot and wear mil-surp polarfleece booties. My feet are never cold