If you’re able to maintain eyes on the incoming WHs and are 99% sure there isn’t anyone else in system with you, yes it should be possible to safely rat C3 combat sites.
I’d suggest starting out here: EVE-Survival: WormholeSpaceClass3
Maybe even consider dropping down to C2 sites to start with, but eve survival is great for listing triggers and make-up of the ships you’ll be facing in each site.
I’d would agree with elitatwo and also suggest a Drake fit for running the sites (I posted a fit here, drop down to Meta IV mods until you can use T2), so that when someone decloaks on top of you tis better the ship costs as little as possible… ECM drones might enable you to get away… maybe.
Regards,
Cypr3ss.