C3s don’t really support more than a handful of people, you quickly run out of content in the hole and don’t have the option to roll for more content- unless you’re a nullsec static. At that point you should just be in a C2 NS/C5, though.
I’d highly recommend you consider C4/C5/C6, it’s not as bad as you think. Especially when you’re in a strong, active group.