Ok Its time for me start thinking about the fuel pump situation ,I'm thinking the KISS method and that would a be a vacuum pump as used on the 640 ,660's and 690 rallys to pump it in to the rear main tank and let the eletric pump take it from there .
I'll have to use the same method as used with the RRuk tanks and let the rear tank drain a little then switch it over to all tanks
then i will let it gravity feed from full untill the fuel light then use the vacuum
pump to drain the front tanks in the rear as a reserve this is the simplest way i can think of , a bit of messing around with two peacocks one for vacuum and the other for fuel but it should work anyway if I'm that low on fuel in the outback i might walking anyway
I'll just have to use a peacock on the vacuum line for the last 2-3L or so of fuel in the front tanks .
Oh And thanks to Lukus who mentioned this a while back .
So i guess the reserve will be about 6L or about 100km only time will tell.