They will be hard to find in some regions, e.g. the Northeast, where larger diesel motorhomes are not very popular. The Western US and the snowbird areas of the Southeast, South Texas and Southwest will have larger selections. So yes, you may want to look elsewhere.
If you use RV Search sites such as rvt.com and rvclassified.com, you will find many without regard to locale (unless you choose to limit the search). Also check major RV consignment places like PPL Motorhomes and major motorhome dealers such as Lazydays (in Tampa & Phoenix) and MH Specialists in Texas.
There are plenty available - just widen the search.
2004 American Tradition; 2013 Buick Verano
Homebase in the Ocala Nat'l Forest near Ocala, FL