I'd recommend SMC or gensacearespammers LiPo batteries. I also would suggest getting a hard cased battery over the soft cells for the added protection.
You can still go to a 3s battery and be ok. U can turn down your esc to level 1 and it is really tame. If you buy too small a battery and 6 months down the road u feel comfortable pushing it a little harder you will wreck your battery.