Flights of drone bombers, routinely hitting multiple towns on all three sides could help spread out the action. Bomber hunters would have more targets and base takers would have a head start on several towns of each enemy chess piece. At least have drone bombers on the large maps, as they can stagnate badly.
If this happens, I would hope to see varied types of bombers, not just flights of B-17's/24's. Example would be; in a section of a front that has high enemy activity, you would see bombers like the B-17 & B-24. In area's were there isn't any activity, you would see G4M1's, Ju-88's, B-25C's, etc.
If the numbers will be based off of bomber's defensive ability/bomb load/survivability, then you'd see a lot more G4M1's show up vs B-17's. Another spot into numbers would be based off of a side's numbers. The side with the highest number would spawn in stuff like the G4M1, Ju-88, B-25C; while the side with the lowest number would spawn in stuff like the B-17, B-24 and B-29.