Well, I'm still semi-ambulatory - so can get some relief from time to time.

Back to the original question - I've now rerouted via MUC to sample the LH internet in flight. That eliminates the long layover at FRA and the question goes away.

Talking with some colleagues, it was looking like the train to Mainz would have worked out OK. Die Bahn is ready to help with assistance and ramps - although they want 7 days advance notice.

details in English by following the "Inter. Guests" and looking for "handicap" at:

http://www.bahn.de/