I have decided that it's time to attack the bottom side. I also want to install a couple of frame connectors to further improve the chassi strength. So, putting the car on a rotisserie is definitely the way to go.
Too expensive for my budget to buy one, so I decided to farbricate it. The shopping list was just 100 Euro of steel
I did some CAD work that I hope can be usefull for anyone wants to fabricate an "e-body" rotisserie, that can be easly unbolted for storage.
Here we go (dimensions are in mm, sorry folks
...):