Ask dealer to run fridge overnight before PDI on propane so you can verify that it is properly cold. Run generator and switch fridge to electric mode to make sure that works. Run furnace to make sure that works, run roof AC and dash AC to make sure they both work properly. Open and shut all faucets and flush toilet to make sure fresh water pump works and shuts down normally. Have them demonstrate the awning deploy stow and lock. Make sure all interior lights, including cargo bay, as well as external headlights, signals and running lights.
Verify that slide deploys and stows easily looking for daylight around seals.
Verify that windows slide open and shut properly and that shades work properly.
Have any needed/promised fixes added to sales contract/purchase order with a specific finish time and add phrase "time is of the essence" before you commit.
Check dealer rep for quick and acceptable warranty fixes if you can by calling previous customers.
PS: Put some miles on rig around town and on highway listening for odd sounds, brake problems, power steering or suspension problems. Park rig on driveway and simulate camping in it for a night and a day before a shakedown cruise. Any new or used rig can have problems.
