Pistoleer Archive

Thanks to those who responded to my other thread I am now a Novice Pistoleer. My question is this, what level of difficulty should my missions be? In addition to Pistoleer I am also nearly a Master Scout and a Novice Creature Handler, as well as half way up the medic tree. So, is right that I am still stuck with the same basically four creatures in the mission terminal, Krevol, Nuna, Ikopi, and Spiders? The level difficulty shows as 12. I know the explorer missions offer more challenging creatures, but what level do I have to be to start getting Peko Pekos, Kaadu, Greater Sharapauts (which I used to get before the creature nerf, and that I can easily handle now), etc? I'm confused.