Great post Gramps!
As far as I'm concerned, depreciation is only germane when talking about the first type of "investment" mentioned earlier, an expenditure made with the hope you'll make money directly from the holding of and eventual resale of that asset or that it will become a productive part of some other business endeavor increasing profits over what they may have been otherwise.
When it comes to quality of life or "fun", we each have to wrestle at the intersection of what we want and what we can afford. To generalize, I find those that speak of depreciation as an evil that must be avoided will either be leaving their heirs a large inheritance or are not realistically in a financial position to allow for the purchase anyway. Regardless, whether in a multi million dollar bus conversion or the most modest popup, we all have access to the same highways, public parks and even tourist traps. If we could not afford our coach we'd be doing the same thing, just on a smaller (cost wise) scale.
We worked many long years toward our goal of being able to enjoy the full time life on wheels to the level of comfort we do. When purchasing our new coach my biggest concern was that we always have equity in it, just in case something happens to me, Peggy will be able to sell the coach and not have to come up with any cash to buy her way out from under it. A large down payment takes care of this. Like was mentioned earlier, paying cash makes no sense, for us (your mileage may differ) because of the taxes that would be due up front and the average return on our retirement investments being higher than the cost of money.
Just take a look at my signature and you'll have an idea of my philosophy on this subject.