How can I securely mount a fan to my pergola without damaging the drainage system, and would JB Weld be a viable solution?

I’m looking to install this fan (1st picture) on my pergola (2nd picture). I was thinking of hanging it from a hook, but I’m a bit concerned about drilling into the frame because of the drainage system. I was considering using JB weld to attach a plate to the center beam and hang the fan from there. Do you think that would cause any problems? Do you have any other suggestions on how to mount the fan on the pergola? Thanks for your help! 😎