I've had a little trouble recently with high seat vandalism. So i've designed a high seat that straps to a tree. Due to the envisaged trouble of getting a heavy seat into a tree I decided to make it from Aluminium.
I had some 2'' inch ali tube lying around from an over order on my part and set about Tig welding tube together around the dimensions of a fishing chair which I knew to be comfy. I used qty 2 3ton ratchet straps which fix top and bottom which clamp the seat to the tree. The seat stays up the tree and access is from a telescopic ladder which needs to taken along (11kg). The seat weighs approx the same as your rifle which to honest was a bit worrying when climbing into it, but I have now had me and a friend hanging on it at the same time (25stone). I was amazed at how solid it felt. it gives a good view for approx 270 deg around. The seat is made from 1'' nylon webbing which is nice and comfy , a bit to comfy if you know what I mean. I also put on a little tray for bins and flask.