Thanks for your thoughts.
I am certainly with you insurance wise. However, I found a Switzerland based company on the net, renting out old sports cars and also some classic bikes from the 70s, so that proofs that there must be a way to get around that problem.
Also, for tires, chains etc, I would want to get a second set of those for all bikes to either swap or change as required.
This would also be done for spares and maybe a whole bike also.
Just out of interest: At the time you rented a bike down here yourself, did you get a nav + pre-programmed routes and accomodation advice with it?