You can have a doodad being hit trigger scripts. This should be enough to get anything you need done, unless you're trying to have something activate-able in the figurative middle of nowhere, since most things you would want to activate are doodads. Alternatively, I see no reason why you couldnt make a square doodad that is completely transparent, able to be walked through, and has no shadow that would then trigger on being hit.
*Caveat: I do not know if objects that can be walked through can register hits, but I assume they can*