I have both the Rand McNally 7735 and the Rand McNally RV tablet. I used the 7735 two seasons ago and used the tablet last season. I am not thrilled with either one. I really don't like the resistive touch screen on the 7735. It takes too much of a push to register a touch. The tablet is an improvement but it's a marginal performing Chinese import tablet so after using a nice tablet for other functions during the day, interacting with the Rand McNally tablet is equally frustrating as using the 7735. There's no question that both Rand McNally products are full featured but they just seem to be old products from a UI perspective.
I have been testing another solution over the past couple weeks in my car and believe that I am going to switch to this for this RV season. ALK just released their CoPilot brand of smartphone app specifically in an RV version. They are selling it for $50 which is 1/3 the cost of the truck version which is what you had to buy if you wanted RV routing restrictions prior to the release of the RV product.
I bought a Samsung Galaxy Tab S2 8.0 tablet and I absolutely love it. It is extremely thin and light. In fact, even though the screen is bigger than the Rand McNally RV tablet, the overall dimensions of the tablet itself is smaller, thinner and lighter. It has a SD card slot and the CoPilot app permits downloading of the entire map on the SD card. So for about $350 you've got yourself a pretty nice setup.
I used to be a huge critic of CoPilot in the past because I found their ETAs to be horrible because they didn't have knowledge of actual road speeds. They used generic road classification speeds. However they now have a setting in their routing profile settings that allows you to turn on ActiveRoute. ActiveRoute is actually INRIX's historical traffic speed feature. In essence this feature ignores road classifications and speed limits and uses a database of actual road speeds by time increment so that predictable congestion is accounted for in the ETA calculation and route selection. I've been using this for trips in my car for the last couple weeks and find the product to be drastically improved when this feature is turned on.
CoPilot so uses inrix Real-Time Traffic Service which I believe is free for 1 year and then $10 per year after that. That requires a data connection though so to use that with the tablet that I mentioned above you would have to have MiFi or Wi-Fi sharing on your smartphone.
ProClipUSA has a specific mount for that Samsung tablet so there is a way to mount it in your RV in a nice way.