OP, What fuel are you using E-85 ? how many pumps if multiples? and why do you think you need a cooler?
The flex fuel sensor is best if installed directly after the regulator,( more isolated from the elements) occasionally you may run into a problem with the sensor flow through being to small this will/may cause the regulator pressure to go up in the higher boost pressures if your 1:1 like most. what regulator are you using? Return line size?
Personally I run a -6 return from my Weldon regulator but the -6 is teflon so it has a larger interior volume then standard rubber-6 and as of yet I've had no issue with a fuel backup into the regulator(^pressure) at over 40 psi of boost and 1100+ hp.