Not sure about how warm they need to be because I don't know what part of the country you are from. LaCrosse has some nice all rubber boots and an even better bet would be muck boots. I am from Vermont and we often have deep snow so I used Lacrosse for many years. I recenrtly got a pair of muck woody max and they are really comfortable, warm and have a good tread. Rubber boots won't give the support needed for steep canyons like in the west though. I have huunted with rubber boots all over northern New England and the vast bogs of Newfoundland. IMO having anything other than all rubber boots in a wet boggy environment is not a good thing. One step in a wet seep and you will go over a pair of leather boots. All my rubber boots are 16" to 18" tall and when in the really wet stuff I tuck the pants into the boot.
On a side note the muck woody max boots go on and come off real easily. The laCrosse come off harder. Don't waste your money on brand rubber boots from cabelas or bass Pro. They last about half as long as the LaCrosse. Recently they started to be made in China and aren't as good. That is why I tried the muck boots and so far like them.