the mounting kit is best suited to composite construction boats but worked fine with my rotomolded boats as well.
very expensive... it may be more economical to retrofit something else.
i have tracrac cradles on the front bar and hully rollers on the rear bar.
normal use is two composite boats but i've had up to four boats on the racks and even a tandem island.
2011 Golden Papaya TI with a 250 square foot spinnaker!
also a more manageable 100 square foot spinny...
the TI3 rear ama mod