Great trailer - I have one
I'm not sure what you mean about "energizing the wiring harness".
This is a well built trailer. There were some reefer recalls for some '07 & '08 models, so double check to make sure that either yours is not one of them or else the recall has been taken care of. Fit and finish have been good. Double check to make sure the molding around the slide is firmly attached. Closely inspect all roof seams and places screws are attached to make sure there is not water leakage. The outside molding on the front of the unit has separated in some units. Double check that ALL lights are working (the reading lights above the rear window may need to be replaced if left on all the time.
Basically, just do a thorough PDI before you pick it up. I would buy mine again in a heart beat. Let me know if I can help answer any questions.