Sorry for the spelling in previous post. Taking the extra liner out should help with more room in the toe box. See if loosening the laces down by the toes helps. Sounds like a tight toe box. Dry your feet out when the weather permits as well.
Different climate and environment than you but if you've been wearing rubber boots I'd probably go with a tall pair of Schnee's hunters. Pack boots are heavy and cumbersome for big mountain hunting but I wear them for pheasant hunting around here and love them for that. Kenetrek MTN Extreme for...
Cannot believe what core strength training does for my lower back. Some chiro helps me as well. My chiro is big into core strength and gave me several exercises to do....huge help. Only go see him when I throw my back out. Core strength is huge for helping with my lower back pain.
Smartwool PHD Hunt socks are money. I usually try to take my boots and socks off once each day to get my feet good and dried out.
Blistering on tops of toes could...could be a bit tight in toe box. Taking that extra insole pit should help.