Hi ,been doin a bit of digging for u .A book came out a while ago called` Vantastic `. In the inside rear cover is a pic of a Christchurch guy with his 15ft Cresta Craft towed with his Chrysler Royal .Pic taken in 1954 going through the Hundalee hills ,nr Kaikoura .. He was also towing a dingy as well !! and says his total length was 57ft (17.4m). I would have thought that your tow rig may be sufficient .? Andy .