Love the moped projects!
I am concerned about the battery pack heating up and vibration. What current are you planning to draw?
I'd recommend drilling large venting holes that would provide airflow, make sure it isn't just trapped since air is also a good insulator.
How tight is the battery in there if it is a bit loose it will vibrate and likely deteriorate your pack.
Enjoyed a few other videos on your channel - I think the hub motor build will be a lot more fun than the BBS02 (It tried a single speed build with one once and it was either too slow or not torquey enough)
I've been wanting to build a e-moped (top tank) for years but they are hard to come buy...