I'd hoped to do more this weekend but what I assume is food poising has been kicking my butt for the past few days. Nevertheless, I was able to get a friend to weld a bolt on the bottom of the chair so I can lock into the EZ Lock in my van.
It's not very pretty (he's not a welder by trade lol) but it'll be plenty strong. He even happened to have a can of spray paint that sorta kinda matches lol.
We also drilled some new holes in the seat pan and moved it back an inch but in use, it didn't work so back to the original position it went. The chair handled completely different but more importantly, sitting an inch back made transfers nearly impossible by myself.