Some interesting suggestions here. I do believe HT has always planned to add some type of towed artillery peice, though a SP gun would probably be more in line with the play style of AH. I also liked the implementation of fixed artillery in the old "Dawn of Aces", where a spotter plane could call in and direct otto artillery batteries placed around the map, but perhaps that is more suited to the static nature of WWI then the highly mobile armored warfare of WWII. There are a number of in-game elements in AH that make a single towed artty peice somewhat difficult to include in an effective way, but it's still worth looking at, IMHO.