My only suggestion would be to be real careful about how much weight you are adding to your unit, both for what you will be carrying along with the storage unit itself. Typically we put a lot more lumber into our projects than the folks who originally built the trailers. Also, I've noticed that the weight limits on the axle and tires don't leave much room for additions.
In our case we have a canopy on the back of out tow vehicle (P/U) and a sliding bed on the bottom, so we can store whatever we want in the and get to it easily. That includes all sports gear, out-of-season clothing, spare everything; even the microwave and other portable appliances go back there. It gives us more room in the trailer and lessens the risk of overload.