Sorry, didn’t get a photo. On mine, the Timber crossmember seems to be higher than yours, so much so that it has a semi circular cut out and the nut is recessed into it. Hence the impossibility of getting a ratchet spanner on to it. With patience, I am sure I could have got it undone but the worry was how to get it back on again. I could touch but not grip the bolt or nut with fingers, so was not prepared to risk it for the marginal benefits that would acrue.
Agree it isn't worth taking the risk as the belt is still usable. It seems there is no thought given to the maintenance aspects. I guess the options are to cut away part of the crossmember to get access to the nut and put in a compensating reinforcement, or remove the rear body panel.
