Side seats wouldn't work.  The boat's too light.  If the wind was up, sure, but even then, the moment there's a lull or you let the sails luff, the boat will heel sharply to windward.  

Side bench seats are wonderful ergonomically, and I get a lot of questions about adding them to the Northeaster Dory, Skerry, Passagemaker, and other light, cartoppable boats.

Mathematically it doesn't work until the host vessel has an empty weight of around 800 pounds.  Starting around that weight, boats are likely to have enough form stability to allow adult-sized crew to sit outboard without risking a wet bottom. (PocketShip is heavy enough, for example.)

Of course, many racing-oriented small sailboats weigh less than 800 pounds and have side bench seating, but the exception proves the rule:  such boats require athletic crews who can shift their weight instantly to maintain balance.  

There are loads of comfortable seating positions in the light boats, blow high or blow low.  If you keep your weight low and towards the center in a Northeaster Dory, you can stay comfortably planted in one place no matter what the conditions.