Get a timber pallet from building site
Put it on the roof have mate stand on it
Few Big Tek screws screw from inside car into the pallet
Job done...
time for a beer
Soft racks will do the job fine for a swag. I know a couple of people who use them with kayaks and over time the weight has caved the roof in a little. You will be right if only using it for a swag. Keep an eye on gummy/fb marketplace they are always coming up cheap, saw some the other day for $20