I agree with Dr. Bob, can it be done, Yep...But should it be done...not unless you enjoy pain. But for anyone looking to do such a trip then they should look to Ben Toland's new boat, I believe with the extra fuel tanks that can be added to it, the range of that boat is reported to be over 500 miles.....But if it were me doing such a trip, I would fore go the second engine and take a 22-25' Sailboat in tow....and if and when I ran out of gas, I could turn the sailboat into a tow boat for the dory.
As long as we are dreaming...might as well dream big.