Here's a couple of thoughts for you...
1. It's usually (always?) less bumpy the further back you're seated. I can recall an occasion when I was at the helm of The Jackeens' 5.05m (yes, the 5cm is very important!) RIB. We had a sharp head sea, enough to make Paul relinquish his normal seat, acting as ballast at the bow. But Louise and Kathleen were quite happy on the rear bench seat.
2. Some friends of ours were once thrown out of their RIB. Last man to be thrown out was the one sat at the back. He had the dubious privilege of seeing both of his mates "eject" and then in a split second realised "uh-oh, me next
Good to hear that you keep a lookout for your crew. I like to glance around regularly, if only to give them assurance that I've remembered them!