I also wear merino blends year around. I find the feet are going to be hot no matter what. The wool prevents chaffing and wicks the moisture away. A liner is the norm as well. When you stop to glass, rest, snack, etc... Take the boots and socks off and let your feet air out. Lay the socks over some sage or a limb for 10 minutes and they'll dry out. Sometimes, miles into the day, I'll stop by a stream or seep and pull the boots and socks off and soak the feet for a few minutes. Usually its cold enough to make them numb and tends to reduce any swelling. Its a fresh start after that.