I do landscaping and lawn maintenance. So I have had countless trailers such as the steel model with the angle iron sides, only much longer.
One thing that you could do to help a lot with towing if you decide to go with that type: Use ramps or something similar to drive the SXS or bike down instead of the gate with expanded metal.
Believe it or not, that gate causes quite a bit of wind drag on the highway. Its not so much the weight you'd be losing. But if you can reduce that wind drag at highway speeds, it will feel much more like the aluminum model.
If I couldn't swing the price of the aluminum trailer, that's what I'd do if I were using it for your purpose.