Trac loc is not going to be a big deal in the snow. Full lockers, to that point, are typically bad for snow. Lockers in ice and rain have a tendency to put you all over the road, they are designed foroff road. That said, the fact that jks have traction control is a huge benefit for snow.
As far as skid plates go...jks have a decent set up stock from a clearance standpoint. Pretty much the best factory clearance on any jeep from the factory. What are you concerned about with skids?