Here is an idea that I have been playing around with for some time. See what you think. What is the problem that most people think about when touring on a fixed gear bike, other than the long riding distances. Gearing choices. If you choose lower gears on a flip/flop you spin out on anything but climbs. If you choose high gears you can't climb. I came across a reference to something that might solve this age old dilemma. There was a solution available to this problem before the advent of Derailleurs.
What I am thinking about is having a fork with 120 mm drop out spacing made and then running a f/f rear wheel with 2 different sized cogs installed as a front wheel, along with the traditional rear wheel in the back. That would allow you to have 4 gear choices on one bike by not only flip/flopping the rear wheel but exchanging the front to back and then flip/flopping that wheel. This would be used for a truly long distance touring bike for cross country rides. Not for general around the town or local rides, unless the definition of local is Rocky Mountain towns. The other thing that would be necessary would be longer than usual rear drop outs to accommodate the extreme chain length variance due to the difference between largest and smallest of the 4 different cogs. The reference to this idea had 100 mm spacing on front and back that I saw. I guess you could do that if you used the appropriate length axles. I think it could be accomplished with Phil Wood hubs and 100 mm spacing end caps if that was your choice for spacing, but I would stay with 120 mm.
What you would do is use the wheel with the smaller of the two sets of cogs on the flatter sections of the cross country ride. 2 cogs can handle most circumstances that you would encounter in the majority of the country before you reach the Rocky Mountains. I know when I rode the Rocky mountains a couple of years ago I was forced to increase the cog size from my normal ones by a couple of teeth, and lengthen the chain, to accommodate the sometimes 5 mile long ascents. It almost defeated me, and if I had not brought along the other cogs, and chain and put them on when I started out from Colorado springs, where I was staying with some friends for a couple of weeks, I wouldn't have been able to ride the area at all. When you get to the Rockies, or some such demanding area, you move the front wheel to the back and take off. I know you can carry chain whips and extra cogs and chains and accomplish the same thing, but that is a lot of roadside mechanics that wouldn't be necessary with this setup. And, you wouldn't need to account for the extra chain length necessary for the newly installed cogs without some extra chain and the attendant changes that entails. This is just one of the things that I waste my time on during those long snowy winter days when I dream about being back on the road and riding long distances to adventure. Probably wouldn't cost to much if you consider the potential, if you were having a frame made or were willing to modify the forks on a frame you already possess. I had a Track fork made recently and it cost under 200 bucks color matched to the frame. I have had stainless steel dropouts made and installed for 35 bucks. So you see, not all that expensive. The cost of the rear hub would be greater than the cost of a front hub but I don't think that would break the bank. Once again, for long distance use, not local use although you could use it locally. What does anybody think?
Just thought I would toss this out.