Hello Aliens, welcome to the forums.
Yes, it's possible, but there's a number of issues with it. Most of all, if it's stationary, then you won't be able to move it, so it would always stay in the Skyranger or (in base defence) in the tank closet. You would have to be able to put it in your backpack, take it out when you want to place it and then somehow turn it into a unit. I guess it could be done if the turret started as "unconscious", and you could just drop it on the ground and "heal" it, but mechanical units are immune to stun and besides it would be rather mood breaking.
But I guess it wouldn't require much work to add code that works similar to stun/heal stun mechanics, just for special mechanical units. We could also give it AI so it shoots by itself.