Silnylon for bottom of underquilt?
My name is Christian, this is my first post in these forums. I've recently gotten in to backpacking and learned two things on my first trip a few weeks ago: 1)sleeping on the ground doesn't work for me, and 2)carrying a 45 pound backpack sucks. My next trip will be a 7-10 day PCT section hike as soon as I finish making a new hammock, underquilt, overquilt, and backpack. I have lots of DIY experience, I'm pretty good with a sewing machine and I live within walking distance of Seattle Fabrics so I hope to have everything done in a month or so.
I have been doing lots of research on materials and have been trying to find a balance between cost, weight, and durability. I want to go with down for insulation but the thought of ripping a quilt 3 days from anywhere makes me weary. By just feeling the different fabrics at Seattle Fabrics I think I would trust 1.1 silnylon more than DWR 1.1. Here are my questions:
1)Should I be worried about the durability of uncoated 1.1 for a down quilt?
2)Could I use silnylon for the bottom of my underquilt in case my hammock sags and it rubs on the ground, and have the top of the underquilt be DWR to allow water to escape?
3)Am I just asking for trouble in western Washington's 8-month long drizzle every fall-spring by both using down and having a vapor barrier on the side with the most air exposure?
Thank you in advance and I appreciate all of the info I have found here.