You want to run at 900psi and place a brazed plate heat exchanger behind your needle valve and before your separators. You are creating a r744 refrigeration cycle where your waste heat will be transferred to what ever is cooling your gas boosters.
Your brazed plate should be sized for the flow and heat load that you have on your ethanol side. You can install a TXV to control the flow to the heat exchanger. Look for R744 expansion valves and TXV’s.