Actually
It's not about an argument - it's about my own experiences of 30 years of boat ownership & having probably nudged close to 100,000Ks of towing my boats as far north as Cairns from Sydney (many trips to NQ) over those shitty inland highways ..... I kinda think that I've learnt a thing or two along the way ie what works & what doesn't . Trust me if the cap was the best solution - I would be using them . I carry them & I've used them - I've also experienced having them not fit snugly because of the difference in expansion & shrinkage to a cast steel hub .
chris