I saw a thread showcasing a life size brute which inspired me to think about species that would most likely be too hard to make a costume for like you said. I think a statue or something similar would suffice and the chair could just be on a translucent stand. The anniversary crown and chair...
A bit gross, but yeah I think it'd be cool and different. No idea how you would go about it, especially if you wanted to go all out Regret style with the chair.