I really can't get over the amount of crap that is posted on this subject by people who have never toured fixed, or even ridden fixed.
I've toured from England, through northern France and Belgium and did 400km of PBP2007, then did some more touring across to Nancy and back to England. It was lots of fun, and I didn't have to worry about maintenance issues despite some wet weather during PBP. Come to think of it, I didn't even have to worry about whether I should be changing gears -- just deciding whether to stand or not up inclines.
I toured with my normal geared bike set-up-- ie, rear rack, two moderately large panniers, three-person tent over the rack (I toured with Machka), and a medium-sized handlebar bag. We were away for around three weeks. Oh, and I also broke in a new Brooks B17 that I bought in London.
I used a 39x17 set-up, had brakes front and rear, and had no problems up or down most hills. The only one that had me off and walking was about 10% looking for a campsite late in the day. It was the steepest, extended hill on the trip, and I made it three-quarters of the way to the top before just hopping off to walk and wait for Machka.
If the OP rides fixed a lot, he can probably go a bit higher in the gearing, say 42X16, but for me the 39x17 was a good compromise. I continued to ride fixed in the year afterwards, doing a century-a-month series, and my 50km round-trip shopping trips with the dual panniers on the back. It made me a stronger and fitter rider.
The bike, a Shogun 400 lugged steel frame, has bullhorn bars, aero brake levers, and Velocity Aero 36H wheels which have proved to be virtually bulletproof. The rear hub is a Velocity singled-sided fixed hub (so there was no cheating with a freewheel or lower gear on the other side). The bike is currently decommissioned, but it about to get a makeover and put back into service because it is fun to ride loaded or not. Plus I need to get a bit stronger and fitter than I am now.
By the way, I was no more weary after a day's touring on the fixed as I was four years earlier touring many of the same areas on my geared Fuji Touring.