If you're not ready for a full aftermarket roof rack, I would suggest some gutter mounts + crossbars.
I actually have some gamiviti gutter mounts (6) lying somewhere around in storage if you're interested:
https://www.gamiviti.com/rain-gutter-towers
The video's now private -- but it looks like you were able to modify the foams from a leather/electric seat (upper back and bottom cushion) to work with cloth/manual seats?