Chilton just re-prints or improves upon manufacturer-published information and there is no manufacturer service manual for any motorhome that I am aware of. There are some chassis manuals, though, and I have seen the RV chassis covered in some of them. Examples include the old Chevy P30 chassis manuals (some can be found in pdf form online for free) and the Ford F53 motorhome chassis manual. Freightliner Custom Chassis has a Chassis Maintenance Manual for their RV chassis too.
But there simply isn't enough sales volume (user demand) to get a Chilton-style manual produced. They would need to sell them in the tens of thousands to hope to break even on the production costs. Especially since they would have to develop a lot of the info and photos from scratch.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL