5rv with the highest R factors

After owning a 5th wheel since purchased new in 2006 I would caution you to not take much stock in the quoted R value. My first thought would be to not put much trust in any numbers that an RV maker puts in their brochures. The RV manufacturer's marketing departments can get very creative without much connection to actual facts. But here is where putting too much stock in R#'s in brochures is a bit foolish. I would encourage you to consider how much heat is lost or conversely let in around the many "poor quality seals" that are prevalent around all the slides and any of the other openings. It is my observation after 8 years with a 4 slide 38' foot 5th wheel that the majority of heat loss occurs at the seals rather than through the floor, walls and ceiling of the RV itself. I think you will also find out that the RV ratings of the walls, floors and ceilings are for the stationary(fixed) part of the RV not the walls, ceiling and floors of the slide outs.
Our RV can be reasonable comfortable in sub freezing weather but if one is physically sitting in a slide out, the floor is unreasonably cold and drafts are very noticeable.

So like everything else in an RV one needs to look a lot deeper than what is in the sales brochure or even owners manuals. Just remember the brochure is a selling document and the data in it may have only a random connection to the real truth and also might be a bit accidental and coincidental.
Another good example of this disparity is in the generic owners manuals that are often supplied by the manufacturers. I would estimate the data in our generic Owners Manual applied to less than 1/2 of our actual 5th wheel. A sad state of affairs but unfortunately too often true. Buyer beware!