I have done several multi-nation starts for Sol, and of the two, the 2nd option is going to give you the most control, and the least carnage.
Use option #1 if you want a hot war in the system after a period of building and development.
Use option #2 if you want control and a realistic political development. #2 is a LOT more work though, be prepared for that.
For option #1 games;
My first game ended in nuclear suicide when the Caliphate nuked the Russian empire. The exchange triggered the other Earth based powers into immediate retaliation, and the earth froze over from the effect of nuclear winter. The intense radiation didnt help...
Game #2 went will a much longer truce period, and went better, but still wound up in a shooting war as soon as the truce ended. Earth got glassed again.
Third game went for something different. I went with a premise of in system terraforming and colonization in the Sol system far into the future. Left the other colonies as NPR's, and Earth as a PC race. That game is still going. Shooting war kicked off when treaty ended, but no glassed planets yet.
My option #2 games;
First game went quite well, until it got huge. I started with too many powers (seven) and it quickly became a logistical nightmare to get through turns twoards the end. There were seven human powers, and 14 NPR's. The turns chugged, and it died a pink horrible death due to database corruption.
My second game went well, but I wound up abandoning it as it was a pretty sterile universe. Few colonizeable planets and no non-spoiler NPRs.
Working on my third game now.