Exhaust question

wondering if I can cut a hole in this wood and put maybe a 6" piece of PVC tube with mesh integrated inside it, then connecting my ducting to the pvc. The mesh would have small enough holes so I can still exhaust out efficiently (450 cfm fan) but any potential bugs won't be able to get in.

Behind it is the plumbing for the bathtub, which is located on the other side of that wall in the bathroom.

Would it be ideal for exhausting hot air from that room (I have a 400 watt MH/HPS with a cool tube that will be exhausted out). This is pretty much my only option, as im renting and I don't want to vent out the windows. It was built 40-50 years ago, one story house with a crawlspace and attic. Anyone else have these type of things in one of their rooms?

Your intake needs to be twice the area in square inches than your active exhuast.

A 6" circle has an are of 28.3 square inches so your passive intake would need an area of 56.6 square inches.

Even if my exhaust is going outside the room? I already have passive air intake by leaving the vent open in the room, as well as running an intake fan. I can't leave the door open because I have 2 cats