I think your idea is very nice! The tank sprite is big enough to allow a complete redesign, and the fact that the head and wheel are 2 independent sprites mean that we can actually put them where we want (imagine changing the wheel sprite into an arm and putting it in the correct position on the body...). Plus since Zenan Bridge is purely horizontal there's no need for up-, down-, left- facing frames (there's no place anyway).
I was going to have fun beating up the Dragon Tank with explosion-shaped brushes in Photoshop (see attachment), but if it's okay to put another kind of robot, I'll gladly try to make something.
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