Creating an "Invisible" Bathtub with no Footprint

Hello everyone! So recently I found out about modding the footprint on objects and created a futon that had no footprint so that it could be walked over, just like a real one. Since that was successful, I wanted to do a similar thing with a corner bathtub. The corner bathtubs look like they can fit two people, so i wanted to create an "invisible" bathtub with no footprint to lay on a visible one to give the illusion that two people are sharing a bath (I thought it was cute, okay!) Only problem is now that I've deleted the footprint on the bathtub, when I try to place it, it tells me that the "object is missing its footprint source." I didn't get this error with the futon and I did the exact same thing, so I'm a bit confused on how to go about this. Anyone got any ideas?