@YoKramer You didn't say which mattress you had but that is quite important in terms of R-value. I have amassed a lot of sleeping bags, quilts and comforters. The only ones that stood the test of time are the ones filled with quality down feathers. The synthetic ones are eventually given away.
I think a a down backpacking quilt might work best for you. It is basically a blanket until conditions dictate you convert it into a semi-mummy sleeping bag. And it's not just one or the other, there are variations in between. I have
Enlightened Equipment brand which is a direct competitor to UGQ but I think either would be fine. But these down quilts don't like to be washed often and when you do, need special care. It is recommended to wear long underwear (top/bottom) and surface clean the bags.
BUT.... if I was designing the MOST comfortable, warm & compact camping bedding, it would be a queen sized comforter, specify 850-950 Goose Down Fill, baffled box construction (not the typical sewn through seams) and it would use 10D Nylon fabric. And then I'd finish it off with a Cotton Duvet cover (optional). IMO, nylon sleeping bag material is not comfortable. And long underwear is only comfortable because it is warmer. So, cotton duvet, for the win. Machine washable.
Not sure where to get that though. Perhaps
Taiga or custom from
Feathered friends.