I run a belt rig all the time.
It has a Dump pouch for mags and various stuff, mag pouches, the radio pouch if it's a game with radio, plus a general use pouch to store papers and keys.
the hydration kit takes care of the rest and even then a bottle can fit in the dump pouch.
my advice for that kind of kit is to wear another belt for the pants, tight enough, that will hold the duty belt in postition.
straps and panels on legs will drag your belt down so they'll work better if the belt is a little tight.
check rigs by typing "pouches on the belt rig" in google you'll get examples