Thats great to hear - I'll give the windows build a try!
By couch-coop, I was thinking one player on the aiming and controlling the different modules mounted onto the vehicle - as it could be a lot to do for that player to just manage the cd timers on different loadouts as the setup becomes complex! The other player would of course handle the driving part, and perhaps there would be various upgrades to modify movement mechanics too.
In terms of game feel, I am thinking the players would do task division and communication that's designed to function similar to Lovers in a Dangerous Spacetime, CastingPlz, and Aegis Defenders.
I am also a huge local coop nerd and think there's not enough of em out there!