I know that almost no one knows how to integrate an ad network not supported by CocoonJS. But maybe we can discuss and create a solution.
Some very lucrative ad networks include RevMob. RevMob is increasingly high paying. More include, Leadbolt, StartApp etc.
I'll start throwing ideas to make this work.
There is an option in MoPub called "Custom Ad Network". It can be used to integrate almost any ad network. However, I don't know if you need to integrate additional code into the game to make it work.