with bangers a take it he races round ovals? if this is the case the cars only turning in one direction, i think baffeling the sump might not be the answer because where-ever you baffel it oil may get trapped when its needed.

i think the problem may be where the oil pick up is, mite be a idea to move/bend/ extend the oil pick up in the sump to the side which the oil is tilted towards i.e on the left of the sump if he races anti-clock wise