Chain them across the back field. As each one is destroyed, we loose some part of our overall radar picture. First you loose the enemy BAR. Then enemy dots. Then friendly BAR. Then lights out. Make destroying one take what 3-B29 can carry max bomb load. Put enough of them in the chain that it takes a strategic effort to put them all down. Then if that effort succeeds, have lights out for that country for 30 minutes, or as players are willing to resupply each location.
Then HiTech would have to trade something off elsewhere strategically to make up for imposing so much effort that the radar command building at the HQ will no longer be the greifing target of ease it once was.
Always wondered what would happen if the only radar on the map was at each base and CV? The HQ is proving the wisdom of not putting in one finger salute choke hold targets that a single player can cripple a whole country by pressing a button.