The data does exist.....sort of.
Wouldn't you fill the tanks in the reverse order they are drained? Say the P-38 manual indicates the fuel tanks are drained in a certain order. HTC most likely uses that order to establish fuel tank loading. Until AcesHigh is fought at realistic distances I am not advocating full fuel tanks. In real life a lot of the fuel load would have burned off before combat ensued. Taking off with 75% just cuts out a lot of transit time and fuel burn.