If it were a boss, I could see it being this two stage thing where you have to dodge shots from the turret for the first stage, and for the second stage you have some sort of missile launcher come up through the turret ring. It could even be manned by the same gunner and just have him look scorched and manic in the second stage. I'd love it to be some sort of running fight- maybe going downhill through some sort of ruins or shantytown.
Spectacular! I've been a fan of your work for a while, and I have got to say that your designs are some of the most thought out I've seen. A lot of artists seem to make really loose designs, but yours are tight, crisp, and detailed. Love the painting work you're getting into as well. In this piece in particular, there's a great use of contrast. Keep up the good work!