Well, I don't like the idea of renaming ponies, especially after they were mentioned, and You've come up with some pretty good names. I know there won't be a "perfect match" for what I had in mind (enough experience and background in multiple skills to talk about pretty much any topic, with lowish social skills). If You say Indigo is an OK match, I can take him. Picture, screen of in-game description, list of friends, and notable skills, please.
As for masons, carpenters and mechanics, I set my workshops to only accept ponies with some skill, and the rest of them with that labour enabled just builds walls, traps, and whatever I need. That way I have high quality stuff, and a lot of workforce.
If he doesn't excel at anything useful right now, let him be a generalist. Military service would be OK too, as ponies with players seem to gravitate naturally towards being guards. I mean, it is Virtue's outpost, and while I have some personal preferences, I'll try to flow with whatever happens. Without fully-fledged cloth industry (which isn't going to happen, as this was supposed to be a mining camp) Indigo doesn't have much choice, but to do some odd jobs around the camp. Besides, a generalist peasant is fine with me, especially that he will become a jack of many trades in time. Oh, and wood creating / burning / smelting are surely in demand in a mining outpost. Same as guards.
He is skilled in Dyeing, so leave that on. We might get some dye and cloth from a caravan.
Above ground forts don't need engravers / stone smoothers, but You might as well enable Stone detailing.
Labours: Animal training / care / dissection, Butchery, Tanning, Soap making, Wood burning, Potash making, Lye making, Milling, Plant processing, Cheese making, Milking, Shearing, Spinning, Pressing, Fish cleaning, Fish dissection, Furnace operating, Woodcrafting (for making wood out of crops), Glazing, Pump operating, all kinds of hauling.
Also these, provided You filter out low skill levels in workshop settings: Carpentry, Masonry, Mechanics, Architect (if You don't have enough architects, or everypony is bad at it anyway), Gem cutting (same, I think You already have a gem cutter), Strand extraction (I don't think this fort is going to get funobtanium, and You may want professionals to extract strands anyway, it takes a very long time).
This is my suggestions, but of course adjust it to Your preferences. for example You might be inclined to keep Lye and soap making to Detergent.
Praise death (that was a joke.)