Actually, let me take another stab at it - we figure we'll own our RV for ten years (on year four at this point), use it 100 days a year (achieved so far in years one through three), and resell it at that point for $15,000 less than purchase price. 1,000 days of RV'ing divided by the $15,000 in depreciation would add $15.00 per night to our costs. I would put forth that that $15 is easily reabsorbed in daily savings on food, wine, entertainment and laundry. All can be done within our RV or RV park for significantly less than would be possible if in a hotel.
Our prior RV ended up averaging us $10 per night when this same analysis was done at point of sale. It was a less outfitted, less expensive RV than our current RV, hence the difference.
Again, though, to compare apples to apples, it seems to me you'd have to apply the same with regard to a passenger vehicle used during a road trip.