Gruul Zoo with Swiftspear (Modern)

This is a hyper aggressive deck that looks to deal terminal or near terminal damage by the end of turn 3. I am going with swiftspear due to its explosive potential in conjunction with the spells I run. I will use Atarka's Command and Lightning bolt to add reach, but I hope to finish my opponent with creature spells, especially with the trample damage of rancor. I did not run Tarmogoyf due to cost and I did not use Strangleroot Gheist because it cannot be used in conjunction with Burning Tree Emissary. What I feel this deck needs are a few more green one drops to balance out the mana generated by Burning Tree Emissary. What I've noticed is if I play Burning Tree I often have one extra forest mana that goes unused.

This deck has played well so far. I beat infect, a mill deck, a sliver deck, merfolk, and a griselbrand combo deck going undefeated in casual play a few days ago. I'm not sure there is much room to maneuver anymore. Ideally I would like to splash white and add Wild Nacatl, but I think it will slow me down and ruin my synergy a bit. Thoughts?