Hi,
I got the mount(s) I needed. Special thanks go to SweMob: Thank you for helping me out on this!
My photographing friend wanted to borrow my TGB for a photoshoot a week ago, so I might just got some pictures of the mount as well.
As the bolt holes differ on the mount base and on the roof itself, the base of the mount was temporarily and quickly mounted onto an adaptor plate made of MDF wood for the photoshoot. Now I'll either have to drill new holes for the mount base and bolt it onto the roof directly, or have to make an adaptor plate made of metal. But either way, it should be relatively easy.
Oh, here's a second pic as well:
Best regards,
Patrik