The 61-year-old was previously found guilty of six charges including indecent assault, aggravated kidnapping and endangering life in relation to the incidents at the remote beach on the SA Coorong in February last year.
In the Supreme Court on Wednesday, Justice Trish Kelly handed down a 22-years-and-four-months head sentence with a non-parole period of 17 years for the attacks on the two women from Brazil and Germany and for some previous offences.
Kelly told Heinze the Salt Creek attacks were committed “solely in pursuit of the gratification of your own perverted sexual fantasies and desires”.
She said Heinze was “utterly depraved” and lacked any moral compass whatsoever.
Heinze met his victims through the Gumtree website, where they had sought a ride to Melbourne, and drove them to Salt Creek.
After setting up camp, he tied up the Brazilian woman with rope and sexually assaulted her before hitting the German woman in the head with a hammer several times and repeatedly ramming her with his 4WD.
The crimes against the two women defied any reasonable or rational explanation, Justice Kelly said.
Heinze was also jailed for an indecent assault in 2014 against another backpacker, who he had similarly offered a ride interstate, and for breaching a bond in relation to a 2014 assault against a fourth women.
Kelly said the nature of how Heinze met his victims called for a warning to young people who used the internet for travel or other social interaction.
“Safety does not necessarily come in numbers,” she said.