And to add on to my post just now, to make tank more effective, instead of increasing their range, i suggest tanks take reduce damage when in blitz mode from bombers and arty, maybe 50 percent and once its stop from blitz, the reduce damage drops to 30 percent for about 1mins. This allows players to move n spread their tanks more strategic without having to worry about taking damage from arty or running away from bombers.
And aside from auto spread from group, developer can make the spread drop from gig. Or even offer 2-3 formation for the player to choose from.