The Sandown 500 will move to November and night racing in Sydney will be put on hiatus in a re-jigged Supercars calendar for 2019.
Tinkering to next year's schedule will see Perth host night racing for the first time and the Gold Coast 600 shifting to a sole 500-kilometre race.
The series will drop from 16 race weekends to 15 with the temporary loss of a race at Eastern Creek.
After a night racing trial at Sydney Motorsport Park this year, Supercars organisers hope it will become a long-term fixture on the calendar from 2020 onwards.
That will depend on whether the circuit can secure permanent lighting, with negotiations underway with the NSW Government.
Barbagallo Raceway will be the sole night race in 2019 - ensuring racing under lights and in prime-time for Eastern states - with plans for late racing at both circuits if all goes well.
The series will begin, as usual, in Adelaide with races on March 2 and 3, and close in Newcastle on November 23 and 24.
The Bathurst 1000 has been scheduled for October 13, as the first race in the Enduro Cup.
Victoria's endurance event will close the three-race endurance series rather than open it next year as organisers look to give the event clear air from September's football finals.
The Victorian Government said having four meets on the calendar - Sandown, the Australian Grand Prix, Winton and Phillip Island - meant the state was Australia's "motorsport capital".
Phillip Island will also see the Mustang, which will replace the Falcon as for Ford entries next year, in action for the first time during a testing day at Phillip Island in February.
"Victoria has a deep history in our sport," Seamer said.
"The majority of teams are based there, along with Tickford and Walkinshaw's road car businesses. Given Ford is based there too, it's only fitting fans get to see the Mustang Supercar at Phillip Island first."
The Auckland meet at Pukekohe shifts to early September into the slot vacated by the Sandown 500.
There are no other overseas trips despite long-running plans to push into Asia.
Kuala Lumpur was added to the schedule in 2016 after a trial the year before, but abandoned due to legal issues.
Reigning champion Jamie Whincup previously urged Seamer to consider south-east Asian events.
"Absolutely we do need more international events on the calendar, we've put our toe in the water in the US and Abu Dhabi but we'd love to do some racing in Asia," he said last year.
"It's relevant, it's in our time zone so anything north of here would be fantastic."
Formats for some events are yet to be finalised.
SUPERCARS 2019 CALENDAR
Feb 28-Mar 3: Adelaide 500
Mar 14-17: Melbourne 400 (Australian GP)
April 5-7: Tasmania SuperSprint
April 12-14: Phillip Island SuperSprint
May 2-4: Perth SuperNight
May 24-26: Winton SuperSprint
June 14-16: Darwin SuperSprint
July 5-7: Townsville 400
July 26-28: Ipswich SuperSprint
Aug 23-25: Tailem Bend SuperSprint
Sept 13-15: Auckland SuperSprint
Oct 10-13: Bathurst 1000
Oct 25-27: Gold Coast 500
Nov 8-10: Sandown 500
Nov 23-24: Newcastle 500
