How to remove rear upper control arm ("Camber" arm)

Hi!

I'm in the middle of a rear suspension overhaul on my mk2 superb 4x4.

Amd I'm a bit stuck.. I'm trying to replace the rear upper control arm, as shown in the picture.

It seems impossible to get to the inner bolt without removing the fuel tank 🤔

I have gotten the nut off and  soaked the rest in wd 40. Hoping that I can just hammer the bolt out. But its impossible to insert any common tool on the bolt. I can barely touch it with my fingers.. so that leaves a problem when I need to insert the new bolt later on.. am I really have to remove the fuel tank? 

This is on the left rear corner.

It seems if though the right hand side is easier.

Maybe modify a wrench to get the job done somehow?