A dash cam is peace of mind, especially when you can see what is happening both behind and in front of you. Hardwiring it ensures the camera stays on while you are parked, which is the best way to catch bumps or theft, but it adds a bit to the installation cost.
November is the sweet spot for electronics, so watch for sales to get that $320 price point down. If you want to spread the cost, you can use the Discover it® Cash Back to handle the payment while you pay it off in chunks.
The 0% intro APR is a deadline, not a gift. If you still have a balance on the card after the 15 months are up, you will start paying interest on whatever is left, so plan to pay it off entirely by then.