If it gives you more piece of mind, sure, but there is no technical reason to do so. Many common-use RV locks have only a few different keys anyway (the #CH751 is extremely common) and you may not be able to use some of the more sophisticated locks simply because the door isn't designed to accept them. And last, I'll agree with Arch that anybody can get into most any RV in 15-30 seconds with any simple tool, e.g. a screwdriver, a hammer, a pry bar, etc.