The woman did not report the incident until she returned home on the state’s Central Coast, and she could not recall the exact rest stop where the attack took place.
NSW police spokeswoman Joanne Elliot said the driver was severely traumatised by the attack.
“Police believe she was so traumatised she’s continued and didn’t report it until [later on] and then she [could] not pinpoint exactly where it happened,” she said.
“We’ve had detectives out all week examining all those rest stops, trying to work out where it could have been.”
The woman suffered cuts and bruises, and was treated for her injuries.
Ms Elliot said the woman was driving a white dual-cab ute, with a Queensland registration, that was towing a horse float.
She said police were hoping somebody from the public saw the vehicle and the particular area where it stopped.
“Anyone who might think back who might remember that at a particular one, if they’re able to ring Crime Stoppers.”
Earlier police said that officers believed there may have been two semi-trailers parked at the rest stop at the time of the incident.
“The men involved are only described as having Australian accents and smelling of body odour,” the statement said.