Maybe there is already a map with this setup, but here goes:

Why?
There could be both an air and ground battle in the center, as the front line vehicle bases can be captured. They can't however, be easily held by a swarm of locusts that immediately abandons it on the way to the next base. This could promote longer battles.
The vehicle hangar at the uncaptureable bases can be destroyed, buying 15 minutes to take or hold the V base it spawns into. That could also be a regular hot spot for buffs and buff hunters.
Even if the numbers are low or nothing is happening on your side, it would be a quick trip to action with your bases so close to both enemy countries.
There is still incentive to take the center vehicle bases, because there would be a spawn into another air base. But that next base would have no outgoing spawn, to prevent the standard cascade of steamrolled bases.
An addendum not pictured: there would be two spawns from each vehicle base into the center of the map, giving another route around stubborn campers.