Derbyfella,
Every birder has a different "convenience zone", and will buy, carry, and use an extra piece of kit to stay inside it.
In my experience most birders, most of the time, need a tripod to use their scopes outside the hides, and then find it easy enough to set up their scopes on tripods in a hide, which is probably why I have never seen a hide clamp in use in a hide. I use a monopod now, but when used I a tripod I occasionally had to mess about with standing two tripod legs on the floor and shortening the third to rest it between my legs on the bench I was sitting on, but that's really as hard/inconvenient as it ever got. I never felt that a hide clamp was going to make it quicker/easier enough for me to want to carry it around between hides - which is the acid test for any of my kit.
Have you used your scope on a tripod in a hide ? If so, how did you get on ?