5 seat configuration
I did this on my -10 thinking my daughters could bring friends, whicy they did a few times. but the issue now that they are older is the middle seat is an issue for comfort over the tunnel. the bench seat doesn't get a friend anymore, sure they fit but they are not motivated to squeeze in the back anymore.
With that said, the bench seat versus two seats and a gap is a great setup that gives the girls some extra room they wouldn't have otherwise.
not much work involved adding the spacer into one of the seats and cutting holes for the belts, but just keep in mInd the tunnel and were folks will need to put their legs, unless it's a baby, than do it for sure, you won't regret it..
CG wise, never an issue and I don't think it would be with three adults.
Pascal