The Jayco rep that said the bubble insulation by itself is R14 either is lying through his teeth or doesn't no jack about what he is talking about. The actual R value of reflective bubble insulation is pretty much never over R1.2 for the best quality double bubble (and I seriously doubt Jayco uses the best quality). Reflective bubble insulation is actually a radiant heat barrier and to function as one, it has to have air space on both sides of it. They higher R values often cited are actually assembly R values and are applicable only when the barrier is installed with the specified air space on both sides. When in contact with the roof decking and fiberglass or foam insulation, the reflective insulation is no longer a radiant heat barrier and, other than a minimal R value that doesn't justify its cost, is little more than an over glorified vapor barrier (and not a great one at that if there gaps on the edges). There has been a huge stink raised in the insulation industry over exaggerated and/or inaccurate claims for reflective insulation and the Feds have finally stepped in to clean a lot of that up.
I don't recall Jayco even mentioning R values recently. Instead, they have been touting how low or high their RVs are able to maintain certain temperatures inside when the RV is placed in an artificial environment chamber, figures that I wonder about because Jayco doesn't mention a lot of variables, such is the heat from radiant heat as well as air temperature (which would simulate sun exposure), the length of exposure, etc.