I like the idea of rings, also you can imitate the bolts holding those rings, But...they should be a bit wider to the scale. As for the gluing to the deck, you might reinforce it with a dowel. Those vents are pretty tall and might be accidentally knocked.I thought about making rings at the base of the fans. I have enough leftovers.
What do you think about it, with or without?
And can someone tell me whether they can simply be glued to the deck?