There's been a few builds lately with seat post issues and some have solved the problem with a post configured like a stem, with a threaded rod, a pinch bolt and a nut and washer on top. The old aluminum Silver King frames were like that and it works well. The pinch bolt doesn't need to be a wedge either it can be a cone, with the post slotted at the bottom. This spreads the force evenly. It seems you may have solved your problem. But this solution may be worth saving for a future issue if you don't explore it now...
Carl.
GuitarlCarl, as always thinking outside of the box! This is a great idea.
Since I will be installing new fork I plan on using the old air suspension fork as a sissy bar and going with either a naner or a seatbench. I will be grateful for any idea on how to make the seat hinged at the front (I think I almost picture it though, thanks to You).