I just looked at the MB 44. 16,500 BTU may be a bit light on burner output for the size of that monstrous smoke chamber, but I would think that with proper tuning of the entire smoker you should see about 275-300* above ambient in light to no wind. The MB 44 is around 16" taller than the Smoke Vault 24", with SV-24 having 18K BTU...my SV-24 will push about 375-400* over ambient temp once it has stabilized. Also, in one pic on Bass Pro site the vent on the rear looks like it may actually be too big, creating excessive draft in the smoke chamber. That alone could expend too much heat. You may look into a way to choke down the vent opening about 50% (I couldn't tell if there's a built-in adjustment plate) and see where that takes you peak temp...just don't go too far or you'll get stagnant smoke (creosote leading to bitter taste on food).
One obvious issue that eluded me until right now: get rid of the thought of using water in the water pan, if you use water. Water cools the space through evaporation and will limit your peak temps drastically. You can put some play sand or pea-gravel in the water pan for thermal mass (rinsed/washed to remove fine particles), then line the water pan with a couple layers of foil to catch drippings and reduce the chance of contaminating the thermal mass, allowing you to keep the same thermal mass for a long time. The addition of thermal mass instead of water in the pan will help to smooth out temp peaks and valleys but will not limit your peak temp like water will. If you use water, I'd start with that. You can add water to the foil liner for increased humidity, if you wish, but with smaller amounts of water it will cause less of a cooling effect in the smoke chamber.
Also, be sure your flame is mostly blue...if not, the venturi enrichment may be too rich and needs adjusted (if it's adjustable), or, the burner and gas venturi/ports may need cleaning of debris, dirt, etc. Spiders can get inside and make webs...mud daubers can wreak havoc as well.
As for the minimum temp of 200*, not much other than a needle valve will correct that, unless the control valve will alow you to push in and rotate towards the closed position to throttle back the burner output..this how the SV-24 burner control valve works. If this is an older smoker that's seen some use and the temp range has changed, a good cleaning and possibly some adjustments on the lower end will help with peak temps.
Eric