NTX just took the words out of my post. The clause was also included in our papers. I think you are completely justified in standing firm about no overnight guests of the opposite sex when your son is there. There are enough other nights in the week that she can have om over, and you would think she would want to focus 100% on your son on the nights that she has him.
NTX has a good suggestion to just ask your attorney to put it in the papers, and let her be the one to bring it up. Don't waste your time arguing with her. And remember to allow your attorney to be the "bad guy" about the difficult matters you do not agree on. As my attorney told me, that is what I paid him the big bucks for.
You continue to handle yourself as a perfect gentleman throughout this journey. I cannot imagine how many people must be scratching their heads at your wife's choice. Hang in there! ncl