I am not encouraging anyone to spend to much on a bike for an RTW, as the cheaper the better in relations to Carnets, image on the road, part avail etc etc
However, if you did buy a bike on finance the V5 is still in your name, as you are the registered keeper, and that what is required in terms of bike paperwork... isnt it? or have i missed something?
Also, if you just took out an independant loan for the bike then that would have no connection with the machine at all and so therefore, the bike is yours to all intents and purposes, surely?
Having said all this, i would go for the new Tenere over the BMW anyway, and i say that as i am in the process of fitting out my 800GS! great bike, but expensive to fit out and a little fragile i now suspect.
Best of luck whatever you decide.
Some day so soon....