Hey:
I drew out a rough sketch on graph paper based on measurements from the cockpit of my S197.
Then I ordered a bunch of extruded aluminum T-Frame and fasteners from www.8020.net based on the lengths I estimated for each section.
Total cost was not cheap, I probably spent around $550 just on the frame and fasteners, and roughly another $520 on the seat/sliders/mounts.
There are definitely less expensive ways to get this done but this is fully customizeable, very rigid, and don't have to worry about it breaking on me like some third-world-sourced POS.
That being said--you can make fully functional frames for a lot less money out of PVC or wood.
I hate to be that guy, but would you mind posting the measurements you took? Yours looks a LOT nicer and customizable than most all of the other 80/20 setups I've seen.