Why the hell are you running that gearing?
So one of my buddies is 350 so he is a big boy. He rides a 4 mill stock cylinder that is just a really mild motor nothing cray. He launches in second all the time with no issues. I am guessing it is a matter of you getting use to the bike and learning how to launch it. Unless the bike is tuned way wrong you should be able to launch in second no problem at all.