I have two boxes on my trailer. One is the "tuff box" style up front between the hulls, from Home Depot, I really like it. The other is a traditional "cross-bed truckbox", like you see on contractor's pickups - behind their rear window, hanging from one side of truck bed to the other with space under it. Example here :
http://www.contico.com/automotive-blow-tb.htmI have it mounted parallel next to sail tube, back end sits on cross bar near axle, other end is up near the tuff box. It's perfect size for daggerboards & rudders, and misc stuff, and it's low profile to fit under the tramp. It's strong enough to walk on, and low profile to fit under the tramp - I hate catboxes that break when you (I) step on them.
It's not quite watertight for rainy road trips, but it is watertight & lockable in the parking lot.
