Could you expand on this a little? Is the oil pump not capable of pumping the oil 20 cm or so into 4G or am I reading this incorrectly?
I believe and I am quite willing to be wrong on this.
Most none aero engines have wet sumps and the oil is pumped directly from there. Aerobatic engines have scavenger pumps in the sump which then take it to a tank which means when you play silly sods a supply of oil is maintained to the bits that need it. And even if that's bollocks its as good a reason as any for me not to do aero's in a PA38.
And as for the rest of your post you are spot on in my view.