After mentioning it on another forum, here's how it works:
https://www.youtube.com/watch?v=kTgBPn9KYLo!
(Oops, sorry about the colour!)
But ...
He says that the trailer is 30kg & the rack is 70 = 100kg, then you have the boat at ~50kg, outboard at ~60, & "all his gear" (including an electric trolling motor, batteries etc, so lets call that another 50kg?
All up, that's 260kg sitting on the roof!!!
I don't know just which car he has, apart from a Toyota dual-cab, but guessing at a HiLux,
https://www.whichcar.com.au/toyota/hilux/accessories/roof-racks says:
The HiLux’s roof load limit is 75kg, and that weight has to include the weight of the rack. So if your rack weighs 30kg, that’s 45kg of gear you can carry.75 vs 260kg & Toyota 4wds have a high centre of gravity to start with!
No, thanks!