There is a real problem of people dropping structures willy nilly in Nullsec. You do not need to own sov, grind indexes, or anything, and yet you can plonk down your own structure in hostile territory at your leisure and gain all the index defence bonuses.
There is no need to do anything, no prerequisites beforehand but simply drop your structure at a time when your foe has no activity and set all your timers to their inactive times of day and you are in business.
I believe this is quite a toxic mechanic and there needs to either be some way to prevent the dropping of structures (with some form of attackable structure like I suggest in the title) or an access list that gives index bonuses only to structure on the list, any other structures should have extra vulnerability in the form of longer windows, etc.
At the moment it is way to easy to grief by just dropping structures with no additional risk apart from the initial anchoring window and the final one.
Having a structure in the hostile territory should be something that requires significantly more defending requirements than the sov holders structures.