The scares don't need to be too complicated for an invisible man.
You can use a lot of misdirection and use clothes on wires for misdirection.
What if they build a puppet system where clothes are assembled like a person wearing them, and hardened by some glue or making them rigid (clothes to become hard in place. ) And use wires or something to move them. Or fishing wire.
People with no budget have made these type of costumes too. There's a lot of ways.
The entire house could be done with puppets and wires for the parts where he's not wearing bandages on his face.