The turret of the now-cancelled Military Police XM1117 Armored Support Vehicle, which mounted both a 40mm Mk 19 and a .50 M2 machinegun would seem top be a better answer. It wasn't so excessively heavy as to make a 4-wheeled MP ASV top-heavy, either or both weapoons could be used by the commander, rather than having to select one to mount in advance [and pray it works long enough to get the job done, as with the Stynker's RWS] and the weapons could be reloaded from under cover- I doubt barrel changes for the .50 were so possible, but that could be arranged if needed.
I'd expect the ASV would require the mounting of a pintle or ring-mount 7,62mm M240- or a pair of 5,56mm SAWs- should heavier weapons not be the preferred choice, and to provide instant response to any attack. But that's a minor detail, easily arranged in-theater at battalion maintenance shops.
