Custom diesel super C builders, 19,500 to 26,000 pounds GVWR

Who will build me a custom diesel super C motorhome on a chassis with a GVWR of at most 26,000 pounds? Something like the Ram 5500, Ford F-550, Ford F-600, or the Navistar International chassis.

I know about Powerhouse Coach. NRC Modifications and ShowHauler only use class 8 trucks. I haven't heard back from 1492 Coachworks yet, but I expect they'll say the same.

Am I missing any companies?

Thanks!