I have a tempress that is mid-back height. I cut a high back down a bit to fit my PFD (longish) and waist throw bag. I wanted both of them above it because I didn't like the forward lean I got with them against the seat. It was a bare seat, with ethafoam and closed cell foam that I glued on. I'd get rid of it for pretty cheap, it's just hogging space in our overcrowded shed and it deserves to get used. It was what I was using before I discovered my preference for low back. And I have plenty of wedging ability between pushing on my frame and the small rear lip of the low back seat. I was surprised. If you come on the Selway, you could try it, and I could even bring that tempress seat for you to look at.
The tempress will fold down when hit, which is good, but only going in one direction.
I am a river, babe - I've got plenty of time, I don't know where I'm going, I'm just following the lines..... - "We are water" by Shaye