Just to update you all, I've decided to accept the technical writer position. The money's pretty good to start, the commute is good, the work would, I don't think, be too taxing, it'd be great for my resume, and give me some good skills I could use for future freelancing. If I really hate it, I'll find something else ASAP. If I REALLY hate it, but can't find anything else right away, I'll just quit. I know I'm in a really rather privileged position to do that, with my incredibly supportive middle-class parents who provide me with a safety net (though, depending on circumstances, they might not be too happy if I just up and quit), something most people don't have and thus have to endure shitty, soul-crushing jobs out of a need for sheer survival, but I've watched my parents do things they absolutely hated to take care of my sister and I, and always swore (and was encouraged to do so by them) that I'd never let myself get stuck in something I loathed. I find ways to make myself anxious and unhappy as it is, no reason to let some crummy job do it for me!
Technical writing is in semi-demand, so even if I end up leaving for something completely different, I could still get some freelancing out of it. And, who knows, I may really love it. And maybe it'll lead directly to bigger and better things. Funnily enough, though, what really convinced me to just go for it was my barber Barb (yes, her real name). Barb is one of those tough old broad types who takes no guff from no one and has seen enough of life to not be afraid of anything. She basically told me that I was wasted where I was, that the longer I go underemployed the harder it'd be to get fully employed, I might just end up liking it, and, even if I don't, I can always change it. Everything in life is a learning experience, and this is something that I can learn from. And life's just too short to be miserable. Sometimes you just have to jump and see what happens.