Honestly, 100% straight forward here, run the proper electric pump with a return to the tank. I know it’s expensive, a PIA to install correct and nicely, BUT, in the end, you’ll thank me and be very very happy.
Personally I don’t know of a mechanical pump that is 100% OK with E-85. There are electric pumps that are. Food for thought.
You’ll forget about the price when the quality and longevity last longer then the memory of the price you paid.