I'll comment on your post-cycle question frist.... After being on Tren for 4 months, you'll be shut down like never before. You're going to need a lot more than Clomid to preserve your gains. I think you'll need MINIMUM 2 months supplementation of Nolva, Clomid, and Liquidex. In the middle of those 2 months, you'll have to do 15 000IU of HCG over a 3 week period.
Now as far as your 15 weeks on Tren question... PM BigAndy and ask him about that. I suspect he'll tell ya you're out to lunch. In addition to that, he'll let you know the problems you'll run into if you run it like that.
Why do you want to run a TREN only cycle, especially for that long?