Hey, digging is a very interesting gameplay mechanic. but it seems to me that it is way to slow, way to clunky and to buggy, if it comes to mount a weapon on the edge, to invest time and effort in it.
Making it faster would be the easyest way to increase its value for now, i guess.
Alternativly you could implement a squad order to dig a hole. So that its faster because the whole squad works on it.
It also could work like the hammer. If you select it you could adjust the holes dimensions.
Would also be nice to be able to adjust the hight of the placement. For example if a hole has a max hight of 10 units, then you can put them all in the ground or let some units stick out of the ground by making a dirt pile on the edge of the hole. this is very usefull if the terrain is uneven in the direction you want to shoot.
Would also be nice to have an order for the tank crew to dig in the tank, to make only the turret exposed and/or to protect the tank against bombs.