It's a bad habit to send random trust invites in the first place.You should always talk to the person you're going to request trust from beforehand. I automatically decline any unannounced trust invites people send me.
Better yet: You can select the area using a numpad drag thing so they are restrained.
Wait... What? How do you do this?
ok. you click on the area of a 1x1. then you press 3, 6, 4, and 2 to change the width/length. then you press 3, 6, +, - to change the height. then it just sticks as a very transparent ghost. thats their maximum room.
Do you do this from the menu of the trust invite?