Haven't read the whole thread but something occurs to me: if I fly alone I need to run the left tank down a bit. I have very accurate gauges so I run it about 3mm below the right one, and then there is no need for a constant aileron offset.
I weigh 75kg. If I weighed double that, I would need to run the left tank down a LOT more, and while one can compensate to a degree using the rudder trim, the plane would end up flying in a very funny way!
This is on a TB20, which has bigger tanks than most. I'd guess than on a C150 or similar one would need to fly with the left tank empty, to have a balanced aircraft. These don't have a rudder trim, either, so it must be tiring to be constantly hanging onto the RH side of the yoke.