Given your pack style, a 3/4 length down quilt is probably best for you--a 34 or 44 liter pack doesn't leave a lot of room for other stuff, so the smallest quilt possible is probably a good idea. 3/4 length isn't "set it and forget it" like a full-length, but it's also not that fiddly--especially at your height. Since you seem to be spending more time in camp than hiking, the extra time setting it up shouldn't be an issue.
I'd look for a quilt with either a DWR-treated shell or hydrophobic down (Underground Quilts is the only vendor that I'm aware of that has hydrophobic down, but there are several vendors that offer DWR shells) to help combat ambient moisture. Also, if one side of your quilt is black, then it's a lot easier to dry it out in the sun if you experience loss of loft due to moisture.
Hope it helps!