Originally Posted by
TURIN
There is also the fact that the fuselage adds to the total lift of the aircraft and there will be a sweet spot angle for the entire aircraft to meet the airflow.
I think this is the key point.
I suspect I have read somewhere that for best efficiency the fuselage is operated at positive angle of attack and it generates some lift. The floor of course could be arranged to be horizontal even with a +ve pitch on the hull, however that is apparently not done:-)