I don’t know how often McMansions appear in crossword puzzles but here is a recent example from the New York Times:

The crossword clue for today new york times crossword puzzle is I merely bought myself a McMansion, and now I’m ___! , and the right or the best answer for I merely bought myself a McMansion, and now I’m ___! is :

INTHEBIGHOUSE

Could also work with “I just walked into the University of Michigan football stadium, and now I’m ___!”

See the full solved puzzle here. And clue here is playing off the theme of staying in jail:

THEME: hoosegow —  fill in the blank clues that treat literally some figurative terms for being in prison. All clues begin “I merely…” and end “… and now I’m ___!,” the idea being that the speaker is talking as if he’s been put in prison for doing something, when the prison term is actually just a literal description of what the speaker was doing.

If intended this way, this would fit how many McMansion critics might feel about having to live in such a house…