I've drilled a lot of holes in my WSMs for mods. It's easy and they've done no damage.
Using a Dremel to make a slot also works well, but it's also invasive. If you are going to Dremel it, might just as well drill a hole.
"Beer is living proof that God loves us and wants us to be happy." - Benjamin Franklin
| Weber 18 1/2" & 22 1/2" WSM, 22 1/2" & 26 3/4" OTG, Genesis S-330 |
| BBQ Guru CyberQ WiFi | Maverick ET-732 |