Was that anti-clockwise. Don't overtighten them Clockwise, if you feel resistance STOP or you risk bending the damper rod.I had another crack at getting these adjusters to turn last night, success! I think I just needed some some "man up" pills.
I don't see why you cant trim the top of the heads down and re slot them. But it will alter how you set the rebound up (if dismantling/rebuilding) With regards to the position of the top of the head. So try to remember how much you have chopped off and use an imaginary line. Hope that makes sense. You would know what I mean if you stripped one down.
Why don't you jack the front up so the bike don't drop down, remove the fork cap, loosen the locknut and remove the assembly and rod. If you do one at a time you can get away without jacking the front up as the other fork leg will still have resistance and hold the bike up, but it does make it harder putting the cap back on.
(:-})