Interesting Prospect. You might try posting on the single speed / fixed gear forum and referencing them here. I recall reading some articles about P-B-P single speed riders which might help you.
You can find gear calculators online and plenty of information on which gear ratios to start with. I would think something in the 65 - 70 gear inches would allow you to go long distance and also keep it reasonable for hills. If you get a flip/flop hub you could run a freewheel on each side with the second one being a lower "bailout gear". I used to run a 39/16 fixed (65 gi) with an 18t freewheel (59 gi) as my bailout. Didn't do long distances but it worked well enough.
I now run a 44/17 for 70 gi with lighter wheels and it is good. I still have an 18t freewheel if needed.
velomine.com seems to be the go to place for reasonably priced SS wheelsets. They had some touring wheelsets with generator front hubs, but I don't recall any SS wheelsets with them.
Good luck.