Well I had a simple idea for a map. It's fictional though but could have been possible if it battle of britian was lost. Operation sea lion.
Have the channel with occupied europe on one side where there are 3 or 4 plane spawns a stuka, two fighters and a He (forgets name) bomber. Ie a junker. Also have a transport plane for one idea for operation sea lion was a giant paratroop raid on britian. Now for the ships a german battle cruiser and a destroyer if designed would work great for the shore landings.
Now for the allies, have 4 spawnable fighters, and maybe one bomber as well as a few tanks on the mainland. There should also be a city inland as the last victory location and off the the side be the airfield. Finally for the allied ships have 3 or 4 destoryers or have a battleship as well and 2 destroyers, and a carrier for more planes. Would be a good mix of land sea and air, and give the german transport plane to have a rear gunner.