They come in a variety of sizes and corresponding GVWRs. It could be anywhere in the vicinity of 10,000 lbs. all the way up to 54,000 lbs., depending on which motorhome you're referring to.

For the truck by itself or when attached to a trailer with a GVWR of less than 10,000 lbs., no... unless you're hauling a quantity of hazmat which requires placards to be displayed.

When attached to a fifth wheel trailer (all of which have GVWRs in excess of 10,000 lbs.), then that depends on the use. For commercial purposes, the answer will unilaterally be yes. For other purposes, we'd need to know the specifics for your situation.

Any commercial use vehicle or combination with a Gross Vehicle Weight Rating or Gross Combination Weight Rating in excess of 10,000 lbs. requires a DOT medical card for interstate operations. Intrastate operations tends to be a little bit of a grey area, although some state laws clearly require it.

If the Gross Combination Weight Rating (combined GVWRs of both power unit and trailer) exceeds 26,000 lbs., and this is a commercial use vehicle, then it will require a CDL (Class A if the trailer has a GVWR in excess of 10,000 lbs., Class B if the trailer has a GVWR of 10,000 lbs. or less), and thus a medical card will be required.