I stand to be corrected but am reasonably certain these ferry tanks would refill the wing tanks and not direct to feed the engine.
Therefore you would use fuel in the wings evenly and then keep topping them off rather than use the ferry tank first and then the wing.
That must not be the case though.
I would expect that fuel is drained from the tank that is currently selected via the installed valve, respectively. SO, to maintain and also avoid shifting of center of gravity, I would start by draining fuel from the ferry tank.
I suspect a mechanical failure in this system that could not be fixed airborne rather than any idiot cirrus pilot or cowboy ferry company theory.
It doesn't really make sense using such vocabulary and it is a cynic attitude, anyway. There is no idiot cirrus pilot nor a cowboy ferry company.
WP