I was the same way-- grew up never having to play that loud mostly because I was never in loud bands. Plus somehow I had a bias against rimshots weirdly... But then I found myself in louder and louder things that really required it.Same here. I would love to do it for some accents because I think it really adds a different texture, but I'm still terrible at doing rimshots. Never really required them since I always played in small rooms with rather quiet musicians.
Any hints on how to practice those? (besides Benny's trainbeats)
It's really not that hard to get going I don't think. Carefully adjust your snare height and angle in a way that gives you a good rimshot with just a slight stroke adjustment. Then ideally start playing in a loud-ass band where you have no choice but to practice them all night long.