Drainback on flat roof

radmix

I'm doing a drain back system on a flat roof. There will be 8 panels installed. I would like to pitch 4 panels to the left  and 4 panels to the right a 1/4" per foot from the roof termination. The termination of the roof will be the supply and return runs.  I would also like the front of the panels 6" off of the roof for the snow to blow under. Ive been racking my brain tyring to figure out how to do this out. Does anyone have any suggestion

Thanks

Rich