we have done a return-less fuel system on a few cars with out a problem but not the is200.
i think i can get around this problem, if it accoured, you would emulate the fuel preasure sensor and shut the pump down. easy.
the only problem i have on mine is that the petrol gague is computer controled and shows im using petrol on when on gas this reset's it self but i havent worked out the inervul it does this
my spelling makes me look stupid but im dislexic hope u can read this