Hight seats are terrible places to spend a few hours, we make ours from steel tube with a shooting rail all round and a lid on the top, we fit the rail with cammo netting and pipe insulation, the acid test is can you get to sleep in one, if not it is too uncomfortable! we fit the seat board so it can be tipped up when you leave so it is dry for next visit.
The very best seat I ever saw was in Sweden where you climbed up into this hut about 12 ft square with a bench all round the inside and drop down windows so you could opt to shut the windy side, in the middle was a stove to keep your back warm, at the bottom of the ladder was another hut with beds and cooking kit.
They know how to do it!