Four months... That's ok, I'd like to share what I came up with.
By the second day of our six-week trip, I couldn't take it any longer, so I purchased an Oregon RMR203HGA
(aka WMR300) at the nearest everything store.
It had (nearly) everything I needed, including a large display, backlight, and records hi/lo for temp/humidity. The only short-sight is that you need to purchase a different sensor to get outdoor humidity. I may purchase one, and move the stock (temp only) remote sensor to the rear of the RV, so I can tell how the A/C is performing. On this trip, I had to rely on asking the kids, who always wanted it colder.
I attached the console in the cab with Velcro, and moved it to the eating-table when parked.
The attached photo shows the sensor location better than I can describe it. Secured by Velcro, just above the rain gutter and in front of the forward coach wall. It never quit or let go through temps ranging 38F-111F and a couple of big rains while driving. If parked with the sensor on the sunny side, or in a paved parking lot for more than a few minutes, the temp would climb, but it was otherwise aspirated nicely and the temps were in-line with my comparisons to nearby WU stations when I checked later.
For $35.00 it worked out well.