Gday Tuffy,
I got a mate to make me a custom aluminium tank to my specifications.
it was made in a vee configuration and wide enough to fit between the floor stringers.
I made a drawing in paint,which i gave to him & it came out spot on.
It cost me about $350 @ mates rates, but well worth it.
The deck fill, breather & fill hose cost about $60
I also fitted a teleflex fuel sender which was compatible with the yamaha digital multifunction gauge,which gives speed, fuel level,range etc and so far has been pretty accurate.
Dave