Many RV trailers come with just enough axle/tires to meet requirements. IMO, you are usually best off to go with a heavier option, when available. Often times the heavier axle will have bigger/stronger bearings, and in many cases, larger hubs, with bigger/better brakes. The larger tires will roll easier, and have more capacity.
I would go with the heavier setup. You just don't want a trailer with a too heavy suspension, that throws the trailer in the air, every time you hit a bump. However, I don't think this will be the case.
Jerry