Towing a camper is great until you feel the trailer push your truck at a stoplight. Adding a brake controller makes towing safe, but parts and shop labor add up fast. Late winter is the best time to book an install, since shops are slow and prices are softer before the spring camping rush.
You should always negotiate shop labor separately from how you pay. Financing the job lets you keep cash in checking for campsite fees while paying off the gear over time.
Remember that a 0% intro APR is a deadline, not free money. If you carry any portion of that $380 balance past the 15-month mark, standard interest rates kick in on whatever is left.