Preplaced on an impassable terrain tile might do the trick. Could be given a ZOC if you want it to zap passing enemies too.
KingArthur... Yes, that could be arranged if the game terrain used in existing Games will allow for it.
The Other thing that is a bit annoying with these types of units is that they must either be fortified where the Clips are not seen or one must use the spacebar to pass on the turn for the unit every turn to see the Clips when set to play with the Default animation.
Not a big deal but certainly would like to be able to have a sign for example that played constantly and was not masked by enemy units. That would open up an entire area of new Units that are meant just for "Eye Candy"
More testing does show that in some cases the AI will capture the unit then leave it but that is basically when they want to go after something else.
The Placement is a key issue so it will not be bothered so much. That and flagged for all Civs and No Hidden Nationality used helps a little so the AI does not believe it is a Barbarian but when it belongs to an Enemy Civ, the AI will go for it anyway.
The Unit Health Bar is another issue that Blocks the Unit when it is Large and detracts from what is suppose to be a Structure rather than a Unit. When 0 Attack and Defense are used the bar is not seen... only the top ball.
Otherwise, I really like this type of Unit for all of the things that can be made to enhance the game
I made a very simple Electronic Billboard that I have been experimenting with. Looks Good and works very well but the above issues are there. IF it is no problem to see a non animated Sign
when it is Fortified, it could be added ok. Trying to decide if I will use it or not
Vuldacon, what´s about setting it as preplaced immobile HN air-unit with zero defense? Does this also block the unit from showing?
Civinator... I use that with the Balloons in EFZI2 and units Block them from showing the same as if they were ground units.