I really like what I see, and the fog is starting to clear!
I will do as you suggest, and regardless, run the line out of the outboard tank in readiness for a future setup.
I will also swat up on Marks work.
Question, if I may .... fuel returns from engine to tanks.
Currently the design is to return to the TOP of the inboard tanks.
If we are drawing fuel from the outboard tanks it would be bad to return to the inboard units , which may be full!
It would appear at this early stage in my mind that another form of valving would be necessary to 'use and return' to the same tanks.
PS: Lynn is Pahiatua born and I have beaut in-law brothers at Fielding and Taupo (both fly freaks).
Again my thanks Frank