I had the double rollers in the rear and cradles up front setup but I added a 1 inch thick foam pad (a cheap cut up swim toy from Walmart) between the rollers and hulls after loading, to cushion any bumps and spread the load.

I once saw a brand new Inter 20 on a single rear roller setup that had been trailered to a boat show. It had two round dents in the hulls where it was bouncing up and down on the single rollers. Ugly sight on a brand new boat!