I have been told that no one will install a Murphy bed in an RV. However, if it is bolted down properly , it should work fine.
The Ameri-Lite 197BH and 192DS both come standard with Murphy beds (as examples). It's not the question of a Murphy bed, it's a question of free floor space. Most "standard bed" travel trailers have mechanics installed under them, such as a fresh water tank and pump (depending on the model). Makes it difficult to modify for a Murphy bed.