Hi Huffalump.
Hi have no immediate advise or suggestions but maybe what happens in the next few weeks of my tour could be of help. I'm presently on tour and original plans (from last year) was to head through Iran but changes from Feb /march meant this is now not possible for Brits so headed up to Georgia, and now in Azerbaijan's Baku awaiting Uzbek & Tajik visas so we could do some of the Pamir highway, the eventually end up in China, but with one delay after another and now being September the temperature won't be on our side, so maybe stay tuned to see what happens to us....we'll no doubt encounter problems that you could then avoid.
Update: The Caspian sea ferry is not so bad, the new port is easy to get to, three Manchester lads we rode with from Batumi cycling to Oz took the ferry last Monday and it took 20 hrs to reach Aktau, on arrival they just had to sit patient on the boat in port for 24 hours while paperwork was done, ferry cost's $120 U.S. and as of July this year Kazakhstan is visa-free for 15 days (for Brits and 9 other nations) We've just come back form the port to check on next crossing and were told to return tomorrow for an update as the incoming boat is delayed.
mark