[Michael Martin]

That looks far too technical for me! I like ideal for folding the wheel away.
No idea how the pivot would work (channel strut construction is alien to me) but you could have pre set angles on a bracket at each end. A bit like how you adjust a rear wing on a race car?
Personally i would like something you could bolt in place. Don't think any friction based mount would be strong enough.

I'm going to subscribe as i'm about to build a rig all be it using wood. So far the seat is on order