my Aerostitch money belt has a 24" zippered compartment... not exactly cheap, and probably a lot of off shore copies available at less price..

I wear a hook/loop closing under belt (Uncle Mikes brand for a competition holster outer belt) as the velcro closure did not scratch my motorcycle tank.. it is very stiff, excellent if you want a belt for inside the pants holster, but not especially comfortable if you don't need it for a specific purpose...I don't think you would like a double stiff belt combination....YMMV