Patrick,
I haven't heard of anyone on this site that added one to a 180BR. I don't believe it was an option on the 180BR either. I am sure if you did an internet search you may find something. Contact the company that manufactures the tower you like and see if they have one that fits the 180BR.
Good Luck, and let us know if you do find something
Kerry
"I would rather be lost on the lake than found at home"