getting rid of the DP (I'm assuming it is paid for?), and then buying another camping unit is... let's just say not the decision I would make.
We bought our '08 knight 4 years ago. It came with a six figure mortgage that still has some payin to be done.
The last 2 years our travelling has been limited due to my work situation. We put the knight in a close by seasonal site, and still "camp" nearly every weekend. It's not just fifth wheels that can go seasonal.
This weekend we are bringing her home, where she will stay until the house sells. Then my wife tells me we will be wintering in Arizona, full time in our knight!
Edit: and no, I don't worry about not putting the miles on. As was said, she's a diesel truck, and like any, she will sit idle for years and fire right up and move when the time comes.