Three clues: Crossdresser, bum, Mexico.

The one that conjures up Mexico for me is Mexican Stand Off (485) though I don't remember a bum or a crossdresser. Come to think of it I don't recall any crossdressers on CBSRMT.

There was a cross dresser one... It had something to do with a man pretending to be a woman to collect insurance money, I think. He fooled a neighbor, or an apartment manager, I think. Robert Morse doing a great job on that. I suspect he was purposefully cast for the role.

He made his voice all high pitched and joked with a friend, or someone about it.