I've spent the last little while thinking about this, since seeing GtE's dream machine.
I'm a DIY guy, so my mind always goes in that direction. A reasonably controlled space like a tent, cab or small room, with wall, floor and ceiling that can handle ~65% humidity, fitted with an exhaust set for ~62 rh and a humidifier set about 58 should be able to do a pretty good job, no? Make sure intake and outflow are both filtered with a bit of natural draw, and it should be an effective and low cost curing space, both in set up and energy costs.
I've been looking at both passthrough wall mount type exhausts and also the inline style, and I think that this will be one of my next projects.
Feel free to point out any flaws in my thought process, it will likely save me some time and frustration.