elcruxio

While some of the effects of alcohol have to do with the personal perception of the effects it has, it has also been scientifically shown that alcohol has a detrimental effect on sleep quality and recovery even in small doses. That is not really something you feel in the morning as a headache. It is something you start feeling after a while when you're not recovering enough on tour.

Though it must be said that you have plenty of experience and are a beast of a rider due to that. But I would be cautious of recommending fixed gear touring for beginners or people whose fitness level is unknown (which I appreciate is not something you did with your comment. This is more of a general comment using your comment as a reference point more than anything else).
I think fixed gear touring or even limited gear touring is something that requires a certain level of fitness to be feasible. Mostly it is to do with leg muscle development and thus leg joint stabilization. Good amount of muscle trained for the action of pedaling a bike will keep the knees safe even when going up hills loaded on fixed gear but someone who does not have that stability yet can face issues.

There was this one time I met two hockey players who had taken on riding a shortish touring route in one day as a dare. One of them had bike he had bought from a friend the day before with three gears and the other had a single speed. At the middle point of the route after a ferry crossing they had to take a break and contemplate whether they'd continue or not because their knees were shot from all the hills (it's not a route you expect to have hills unless you've been there). We gave them painkillers and they asked us whether the route would get easier in terms of elevation. I couldn't say then because I couldn't remember but as my wife and I rode it to the end the route just got progressively worse. I felt really bad for those dudes.