Haven't been on this forum in quite a while - I loitered quite a bit when I was looking into purchasing a Joyner, but went a different direction.
In any case, I was recently out at the Coke Ovens, as well, and had an absolute blast. Great trip - well worth getting out there. I posted about my trip out there on a website I keep for sharing these trips with friends & family that can't get out with me: http://tomcarfun.com/Coke_Ovens.php
I didn't make it to Martinez Cabin - but I plan on getting back out there soon for that leg. I headed Right towards to the Coke Ovens, after passing through Box Canyon. Next time, I'll head left, towards the cabin/mines.
Lots to see out in that area! Many, many trails, and lots of interesting sites to visit.