If you take the rear silencer and the rear undertray off, it'll make life a lot easier but I can't remember that there was enough room to route the brake pipes through, without taking the tanl off.
The brake compensator is underneath where the rear passenger sits and it has 2 pipes in from the reservoir and two pipes out to the calipers. Those pipes run along the top of the rear subframe (some plastic "u" clips hold them in place) until they emerge at the trailing arm bearings.
It might be possible to feed a new pipe through the gap between the tank and the body, then over the subframe but I dunno how you would steer it out the other side in the right place, or hold it in position, since you need to press it into the clips on the subframe.
I've got the same job to do and I'm reckoning on dropping the tank, subframe ansdd everything.