The Thorlo's are actually a bit thicker than the Fox River socks they issue you. Once you get steel feet, you could pretty much wear whatever you want, go barefoot, it won't matter. I actually prefer the Fox's though I did the same as you and bought Thorlo's prior, which I still wear. You don't need liners, you won't have time on humps at OCS, or ever for that matter, to put on an extra pair of socks, too much time. I, again, bought Fox liners, blisterguard, and I won't even wear them with my dress shoes, they make your feet frigain sweat. As for the boots, use the insoles, but just something to think about. I got a brand new pair of Jungle's during TBS because my OCS Jungle's were pretty worn out. The new boots are much much bigger than the OCS ones. I guess the constant wet dry wet dry from OCS shrunk them. It's weird, they are about inches shorter than my new ones, and they are the exact same make, model of boot.