Hi Nick, That sounds a bit too high tech for me!
 
I have done some research and it seems you can wire in some resistors in parrallel with the sender unit to reduce the resitance to that requiredn to work with the gauge.
 
http://home.mindspring.com/~purlawson/files/Fuel%20Sending%20Unit%20Resistance%20Matching.pdf
 
I need to do some maths but in theory it should work.
 
Cheers,

Matt
 
 

I run a datto 1600 tank which allows me to connect to the rhs filler hole. You can still squeeze a spare on top, more so for transport in my case. The gem neck is too high so you'd need an in boot filler or mod the panel work in some way to fill externally. Watching with interest the gauge. FYI for $20 boating supplies sell a stainless filler cap/ neck which fits sweet in the std rear guard hole

RallyRs,
 
I have been on the look out for a Datto or Capri tank when this Gemini one cam up for $15.00.  Even if I never use it I'm not stressed.
 
Can you post some pics of your setup?  Is it posible (legal) to use silicone tube to go from tank to filler?
 
Cheers,
 
Matt 

Datto 1600 tank in esky boot

 
Stainless boat transom filler. good for track because it screws & has an o ring seal. Drive you nuts on a road car because it uses a special 2 prong key to unscrew it. 
 
 
the plumbing

Cheers Mate,
 
But photos didn't work...
 
Matt