I have the same aircraft and fuel layout as you.  I have the Skysports system with the probe in the main portion of the tank only.  You can calibrate the tank to read full when the fuel is at the neck of the fuel filler in the outboard tank and you can also calibrate it to read empty by putting in say 5gallons of fuel and pumping out until the pump loses suction.  To give yourself a safety margin you could then put back in say 2 gallons and set the gauge to read empty.  Your choice, but in no case should you rely on the gauges as an accurate measurement of fuel remaining.  I have a JPI fuel totaliser which is as accurate as the amount I tell it is in the tanks at the start of a trip.

 

Make certain that the duct from the outboard tank to the inboard tank is as big as you can get it.  Mine is a little small and I have to wait for the fuel to run into the main tank.  No real hassle but worth looking at whilst you can.

 

Ian Crowe

LNC2   C-FKRO