I have a never mounted Sharkskinz tail that retains the stock seat. Besides the screws on each side that bolts to the subframe. What else mounts this thing? Just those two screws?

Yep, that's it. I use zip ties in the front to hold it to the frame. YOu may have to drill some holes on it.

i fiberglassed two tabs to the inside of the front and used the tank hinge mount to hold the front