my seat on the rear bench is directly in the center... and one of the guys I fish with is a good bit bigger than me, so that's why he drives. He puts me on plane - I don't get on plane with just me in the boat because I have 2 large batteries up front, and my butt doesn't weight but 180, so I even the batteries out.
I thought about putting another seat base to the left of the motor (facing the motor from inside the boat), but decided against it because with his weight being more than mine, it would lean more to his side and me being more up in the air so to speak... I'm just going to keep getting down in the floor - we don't make long distance runs enough to justify me adding seat bases
Now - if you both are about the same size, I don't think you'd have a problem with it. One other reason I didn't add it was because even though my boat is wide enough (my rear bench is 5' across the top), it just looks like it would still be cramped. I'm picturing him sitting in the middle and when we have all of our gear on the boat, there just isn't enough room
but as far as planing goes... the more weight at the rear of the boat, the faster you get on and stay on plane. We tried it mulitple ways - me driving and him in front (NO PLANE at all)... and him driving with me in the front - it planed... i'm just that much of a light weight I guess... and all of that is why he drives