In a meeting at Hampden Park the SPL chairman also proposed a play-off system involving the team to finish second bottom in the top flight and the three teams behind the winners of the First Division.
The developments come just days after the 10 clubs who will make up the First Division next season threatened to quit the Scottish Football League.
But the financial benefits included in the new system, which remains 12, 10, 10 ,10 should gain the approval of all 42 clubs.
SPL independent chairman Ralph Topping said: "I am pleased that SPL clubs have today agreed on a way forward for the game in this country.
"We have tremendous sympathy with the SFL1 clubs and their plight and with their shared ambition for a 42-club solution.
"Much work needs to be done in a short space of time to achieve our objective of a single merged league this summer. But, where there is a will, there is a way. The time for action is now."