Did you use OTT's DIY tune devices or did you go to one of their dealers? I read where you tuned the rental so I would assume you have their device. If so what is involved with purchasing and using it?
For sure if you can get it sold as package that would be ideal. That's a big difference in price between 24 and 25 in your mileage range. I would ask 47K and expect to negotiate some.
I think you may be more successful pulling the camper and selling it separately. Most people don't want a pop up truck camper and if they do they usually have a specific type in mind. They may really like your truck (I do for sure) but think do I really want to haul that around when I'm not...