As far as age, unless you are having problems and it is costing you more than you feel manageable age in and of itself is not really a factor. Most people trade not so much to maintenance cost but because they want something newer and with maybe more whistles and bells. All come with a new cost factor. The real question is what you can afford and feel the cost vs. the enjoyment is.
Now as to the comments on not financing a motorhome or no mortgage, as a financial anaylist retired, I must disagree. Why would you want to lay out several hundred thousand dollars on an asset that has not chance of appreciation. Even though you might have a mortgage cost you also have the reality of the asset liquidation in the event of your demise. That may ultimately be passed to the mortgagor in that event. All depends on your estate status. This too is contingent on your financial position but many if not most cannot afford a multi-thousand dollar outlay.
