Help please! 4040 clamp/latch

[Port1s]

So I'm building a folding/portable rig to my own design. Basically I need something more sturdy than a playseat challenge but much smaller than a full rig - and foldable.

I'm happy with the whole design, apart from I need to be able to clamp or latch together two parallel peices of 4040, across their faces, if that makes sense. It's where the wheel folds down, so needs to be a quick release option, as I need to be able to get out to take a pee. However I can't find a suitable clamp anywhere.

I'm effectively looking for a clamp/latch where the distance between the bolt holes on the latch and the hook is 40mm.

Any ideas? Are there specific catches that are made for aluminium extrusion?

Any help gratefully received!