This is part of the game mate, so i'm afraid this isn't possible. Unless i've misunderstood your request it sounds like you want to eliminate the 'fog of war'? (for lack of a better term).
The game relies on line of sight - Just because you are taking fire, you don't necessarily know where it is coming from, as is the case in real life. Sometimes an enemy might suddenly appear on map because your troops/vehicles spot them when they fire, but more often than not if they are in trenches or operating an AT gun, they will remain hidden until you have a clear shot and have identified the enemy in their current position.
That being said, because you almost always know a trench near the enemy line will be occupied, you don't need to have spotted troops there to start shelling the position. Same goes for an obvious AT emplacement. This is when the attack-ground command comes in handy, or an artillery barrage over the position.
Some people have pointed out there are instances where an enemy should be constantly spotted as they themselves can "see" where the enemy is when dropping the camera down to the unit's PoV. But keep in mind these are WW2 tanks and the view slots are quite small.
Here's an example from (i think) a tiger tank.
Gunner seat:
Driver seat:
As you can see this is going to make target acquisition tricky which is why many people will rely on the attack-ground command on stationary targets such as AT guns or entrenched soldiers. Enemy tanks on the other hand, are usually more easy to distinguish and because of this, can be found and tracked once they make an appearance on the battlefield.
As far as i can tell, your units all share information on enemy positions despite comms not being perfect back in WW2. So if you have 4 vehicles coming over the top of a hill and facing suspected enemy positions, the vehicle on the far left might spot something he cannot yet target due to an obstruction, while the two middle vehicles
can target it.
Some people bring infantry units to the front line for this very purpose, less costly to lose and they usually do a good job of staying alive and spotting targets when they are crawling on their bellies towards the enemy.
Coming from ToW2 Africa, i too had to struggle with the more dense environment and easily hidden enemy units - Quite frustrating when on the attack, but great fun when you're laying in wait to ambush.
I hope i didn't misunderstand your question, if so that would be a huge waste of time for me to write and you to read
But hopefully it helped.