i went with the 38c and the sks p50 fenders this time.
For clearance i found a thread that talked about heating the fender and shaping it rather than cutting it. I think it is going to work out great.
I took the fender and put it in place (and didnt bolt it down). I deflated the tire and sandwiched a folded rag in between the deflated tire and the fender so it fit real snug.
I took a hair dryer and started to heat the fender slowly at the fork crown as i inflated the tire while mounted in the fork. The tire was inflated to max psi and the rag was putting tons of pressure on the plastic up into the fork crown. I let it sit for a day. The next day i repeated this process and let it sit and it created a nicely shaped fender right at the fork crown with plenty of clearance and didnt warp or mess up the fender.
Seems to have worked great.