Your Collector Sim's Private Museum

Alright, so I built the museum, it still needs a lot of work, but it's making progress. My only issue is that I can't find the option to keep visitors off the lot. Does anyone know of a mod or something that keeps visitors off the lot? I'd love it if I could have a modder make a buyable sign that keeps visitors off the lot when that sign is on the lot.

http://thefoxsims.weebly.com/uploads/4/0/0/4/40048961/4975320_orig.png