Find someone who's a security guard. Shirt and trousers are all generic, the biggies are going to be kevlar vest, realistic shoes (NEVER shiny, that can give away your position), and an equipped Sam Brown (the web belt can weigh close to 30 pounds loaded). Ever thought of just giving him blue jeans, sneakers, a tactical holster and a Polo shirt that says "SHERIFF" (or "POLICE") in big bold letters across the back? That's what half of them wear any more. Or just borrow something from a retired cop.
I'm a 34" waist, medium shirt... but I'm 3000 miles away.