and Tim, hope you are still reading.

for a bunch of years now, I use a couple of colour coded net bags that are very light, to keep smaller clothing items in and to stop the migration and being hard to find, socks or whatever.
Keep socks, underwear in a yellow bag
warm stuff, neckup, gloves, whatever in a blue one.

my civvie clothes are usually at the bottom of my clothes pannier, my extra riding kit , shorts, jersey, on top of civvies,

small dark stuff has a bad habit of getting lost in or under other stuff, so these separate bags really helped keeping track of stuff, and in the case of my "keep warm" stuff, its nice to just be able to reach in, grab the "blue" bag and get whatever if needed.
I even use these bags for my commuting, especially handy for the warm stuff as I ride in all kinds of temps, down to -10c or more, so not wasting time is nice if I need some overmitts or different mitt liners or whatever.
Handy too for keeping my wallet, cell phone, seat rain cover, glasses case etc in a yellow bag, again for saving time and not rooting around searching.