Grand Proposal has the distinction of winning the inaugural Highway Handicap and will be out to claim another as her lead-up to the Country Championships.

The Neville Layt-trained mare is one of 28 nominations for Saturday's 1200m-race at Randwick restricted to country horses.

After her win on October 17, Grand Proposal was unplaced in a benchmark race before running third and second in two more Highway races.

"She has had a nice let-up and is absolutely flying," the Queanbeyan-based Layt said.

"After this she will run in the Country Championship heat at Goulburn two weeks later and hopefully get into the final.

"It's exciting for country trainers to have these races."

Layt's biggest problem will arise if Grand Proposal wins both her next two starts.

"If she should happen to win both we will have to sit on the fence until the Country Championship final in April because she will be a class five horse by then and you can't be higher than that," he said.

Premier Sydney apprentice Winona Costin, who rode Grand Proposal to win in October and was aboard when she ran third the following month will be reunited with the mare.

"Winona's 1-1/2 kilo claim will help her because she will be among the top weights," Layt said.

Among her opposition is the Greg Bennett-trained Invienna who finished second to Grand Proposal when they met at Randwick.

Trainers from the south-east of NSW have an enviable record in the Highway Handicaps with Layt saying one of the reasons could simply be the highway.

"It's pretty easy for us to travel and might not be for others from the north coast and places like that," he said.

"We don't have any mountains or turns. It's a good highway to travel."