EDIT: someone joined, thanks

this is seriously frustrating. Why can't i open up the last spot to public?? I don't wanna keep remaking games like this and hope my friends join fast publicly

Did you consider the option of starting your game with 1 less player?

If a game isn't full when you decide to start the match then the map is regenerated to balance itself for the new player amount. You are also given 8 hours before the game starts so that everybody in the game gets a chance to see the new map before it starts. I know 8 hours sounds like a lot but if somebody is sleeping they need the time. Also, in a game that will last over a week the extra 4 hours isn't such a big deal.