So I'm looking for what one would think would be a common component, but one that I can't find anywhere. Where can I find a steel 26" threadless fork (EDIT: 1 1/8") with eyelets at the bottom and halfway down, for a front rack? I could get a surly LHT fork, but that's really expensive. I'm amazed that these aren't everywhere; surely it's not that hard for the manufacturer to add a couple drilling in the fork?
What also blows my mind is that the only ones I can find (apart from the LHT) are suspension-corrected, which seems to mean that there's more of a market for turning suspension mountain bikes into touring rides than rigid mountain bikes. Rigid-fork mountain bikes seem like the obvious choice for touring, in my mind.
These guys do touring-specific parts, you could email them and ask about forks, you might find they can order something for you.
Also, the Carrera Subway has a fork with all the fittings you want, and it would probably be cheaper than the LHT one. Halfords might be persuaded to sell you one without the accompanying Carrera, and despite the reputation Halfords bikes have, it's a decent fork, made of 4130 cromoly steel.