How about rubbing the porcini/rosemary/pepper on the beef before the overnight refrigeration

It depends on whether you are using fresh or dried herbs. This sounds obvious, I know, but dried herbs and dried porcini have an intensity of flavour that can be anything <4 times that of fresh herbs. Rosemary is a particularly intense herb in it's own right. Go with what you think is best and the flavour you want to achieve. I personally would add the rosemary later on in the cooking procedure.

I don't see why that wouldn't work!