Air travel and most brand-name hotel chains will cost you more than visiting down the road with your RV.
So very much depends on the specific RV you are comparing. For an inexpensive small trailer you're probably correct, if you don't take the tow vehicle on the car/motel trip but use a small car instead. For a 45' DP motorhome the numbers are rather different.
For example the Beaver Patriot I had (45' DP, 525 HP, 50,000 lbs max) got 5-6 mpg such that a full 150 gallon tank could get you over 700 miles with some reserve, if conditions were right, but adding 125 gallons of diesel at one stop will add up, usually over $400, depending on price.
And the above doesn't count tire wear and annual maintenance which, sometimes, varies with the miles covered, nor does it cover insurance, licensing ($1200 per year plus in Colorado).
The only way your figures work with something like this is IF you figure that you already own the RV and do not include the fixed expenses (including depreciation, etc.), and keep the car/motel trip to a small car (25+ mpg) and Motel 6 or such.
Or to state it more briefly: So very much depends on what RV/tow you are comparing with what vehicle/motel you use, as well as whether you consider that an RV is already owned or that you must include the cost of getting and maintaining an RV as additional cost.
And yes, I see that you have a DP and a Kia.