I think having a seat on a traditional stock frame like that would only be a nuisance. If you're going to have a seat, put it at a height thats comfortable to sit on. a seat that low would not be comfortable for sitting, and would just get in the way.
Well, I would do with it much like I have my Alibongo set up: a seatpost short enough to be slammed down, but with enough length to allow the saddle to come up enough to give a bit of use when riding to spots.
I have one stock bike set up without a saddle and singlespeed, the other with a saddle, gears, and smoother tires for urban riding.