Do it. We just did the exact thing in January, saving over 6 grand after fuel costs were deducted. I called my local dealer (who, by the way, didn't sell me my prior trailer either) and made sure they'd continue to do my work. Also made it very clear to the selling dealer that anything would be fixed before I left, and that if they changed the deal on my trade drastically, the entire deal was off. We had to tow our trade down with us. We bought used, so it isn't likely warranty work (other than extended warranty) would have been required anyhow. As others have said, we were prepared to stay if things needed repair, and we were prepared to haul the old camper right back home if we weren't happy with the deal. We didn't stay a weekend due to weather, and the walkthrough being totally fine, but we would have if needed.
A side note, you may (if you haven't already) want to mention to the local dealer that you are considering the long drive, telling them the price and seeing if they'd match it. If they don't have the upgraded edition or won't order it for you at that price, flat out inquire if service and warranty work will be an issue. I can't imagine they'd turn away future business that wasn't warranty work.