Sounds like the clearance is only an issue when you are loading and unloading the boat from the trailer. Can you remove the top cross bar when loading and unloading the H16 on the botton. Reinstall only when doublestacking.
This is an option- uninstall the rear section for the majority of the time and only install when double stacking. It isn't possible to only remove the rear crossbar though because it gives support to the two rear uprights and the long bar that goes from front to rear.
But....it would be great if I could come up with a way to not have to take apart the trailer just to use the double stack.
