I was thinking it would be a cool idea for a guild to claim a tower or a keep then be able to choose spawn location of cannon or mortar.
To break down ground rules of making this not OP first 1 cannon and mortar not be within range 2500 of another cannon or mortar.
Cannon can only be placed on a wall that is not destructible.
Mortar can be placed Anywhere inside of tower / keep..
So 1 cannon + 1 mortar can be beside one another but you can not have 1 cannon beside another cannon within 2500 range limit to explain that further.
Now this upgrade only work Before tower / keep is upgraded. you would not be able to just move it on fly otherwise it be straight broken.
Also if you unclaimed tower / keep it will reset spawn location to default before upgrade after upgrade it will stay that way until tower / keep is capped.