There are some custom tailors that do alot of work for EP, cops, DSS, and USSS types. One that I've used with good results is Hong Kong based, but does a traveling roadshow around the US 2-3x per year, doing sizing and fitting by appointment, then ships you your items a few weeks later. He's got a full palate of colors, fabrics, price points, etc. and does shirts also (Note I HATE the fit of off-the rack shirts, way too baggy...) Its not uncommon to walk into an appointment with him and see guys doing a fitting in full belt/kit and low-viz armor, and they'll be simulating a shooting stance/sitting/squatting (crotch tightness is problem with the trend toward tighter European-cut suits...), and then getting into the finer points of size, quantity, and placement of pockets and belt loops. You'll want to do same if you want anything to fit right while actually working. I know he's coming for another round in July-Aug. PM me for details.
I don't have a lane in this topic but I have to comment. When someone OWNS a niche because they do it right, you have to applaud. What a businessman. It sounds like he comes prepared and provides the service. I have no doubt that the price will make you blink the first time, but after the service and product, you'll be lining up again and again. I love it.