50/50 headache

Having some problems.... got a guy wanting 50/50 shirts, blue with white print (4XL sizes too...). Decent sized lettering on the back. I figured it'd be safer to use a flex white vs regular. But this flex white is freakin thick as crap. 1st pass is way ghosted, flash, 2nd pass is thick, chunky looking, rough in places just terrible.

I guess my question is should I just use regular white? Or buy some reducer or something for the flex white? I'm flashing with a heat gun and final curing with a heat press if it makes a difference...