First of all, plumb your return from the engine fuel distributor to dump into the surge tank.
When you need the surge tank, the flaps are working for you to trap fuel (therefore not a lot of extra help is needed). In a cornering situation with less than a half full cell, the fuel inside the fuel cell will be on one side or the other for the length of the corner (measured in a few seconds). If your surge tank pump pickup is in the wrong side, it will cavitate, otherwise pump into the surge tank. The surge tank volume is around a gallon and will probably hold half of that in the same corner (unless you put a top on it -hint hint). In the few seconds that you are sucking fuel from the surge tank in the corner, how much fuel will your engine burn with the excess being pumped back to the tank? A gallon? No. No need for much extra being pumped into the tank from the aux pump.

Best feed for the surge tank is two low pressure pumps picking up from each rear corner of the tank. No cavitation. If you only run one aux pump, think about the track and put the aux pickup on the predominate outside side of the fuel cell.

This set up works very will to empty your fuel cell. The down side is that you may not have two miles of fuel left when the engine coughs as you pass pit in.