2016 136 HT Gasser
I've had experience with bungees and rubber tarp straps in the airflow vibrating and causing a lot more noise than you'd ever think they might. They both also loose a lot of their stretchiness/holding power in the cold. A ratchet strap or two would hold the boards down more securely. Put a twist in the strap wherever it's in the airflow and you will reduce the likelihood of vibration and noise, too.