Do the 5in naval guns ever "camp" an airfield? It is very difficult to get 5in guns coordinated let along close enough to the end of a run way to "cap" it. I've seen it where the 8in guns from the cruiser have the end of the runway zeroed in but even then planes get up between volleys.
The Panzer IV has long range smoke, and the Storch can mark them well enough too.
I dont think arty would be as dominating as you think, it would still have to be used in conjunction with other systems.
And, it would horribly vulnerable to counter-attack. Towed arty if not just thin-skinned; it's no-skinned! Unless several players cooperate to protect it, just about anything with a gun on it can take it out. In the DoA implementation I wrote about, it was not at all unbalancing, though in that case it was also not mobile. What might be a good way to maintain balance with mobile arty is to only be able to spawn one gun per player. To be affective, a group of players would need to set up close to each other, and share az/el info from the spotter. I would note that, if an M3 is used as the tow vehicle, you could always jump in the MG to protect it, but you would not be able to fire the arty while doing so.
Another idea is for a player to be able to "build" a protective berm around his/her towed gun, if they remain stationary long enough. Imagine that you pull up within arty range of your target. You press a key that deploys your gun (similar to lowering or raising landing gear, though it might take a bit longer; say 1 min), which effectively immobilizes the gun until you "un-deploy". A second key press begins construction of a protective, 3-sided berm around the guns (time to complete, say 5 minutes), providing some protection from direct fire and near-misses, once it is complete. The gun could not be fired while the berm is under construction. You can still bug-out with the gun (after 1 min "un-deploy" time); the berm would simply disappear as soon as you begin towing the gun away. This would have a bit of a "Command-and-Conquer" feel to it, I think. This idea of being able to construct temporary facilities is what's missing from the air-land battle of AH, IMO; it was the idea behind my FOB suggestion from several weeks ago. I.e. a deployable, but temporary base to conduct limited operations from. It would add a dynamic element to the MA that is sorely lacking.
