How about a better description of your set, or some photos?
A #2 is way too big for marten. I have a few #1 1/2 LS marten traps, and I always get a few that crawl back through the jaws or a spring before they die, so I have to haul the whole mess back to town and thaw it out to get my trap back. A #1 is the perfect size, but I'd try #0s if I could find them.
You don't really need guide sticks or covered traps for marten. Just make the trap pan a convenient (or, better, necessary) place to step.
Most pitch gets in the fur after it's caught. Keep them swinging away from conifers. If you have a marten or two, you might try removing it. Just don't make a bald spot. I just fluff em up and let em go, and seldom (never?) get docked for pitchy marten (then again, I'm pretty good at keeping them clean while they're in the trap).