Great question and the answer is yes.  

Your Epsilon P300 if it has a Flex 4 seat should have a D Ring on each side.  Here you can attach the back band Baffin backrest 

You would simply remove the existing BackRest from your Epsilon and install the Baffin one

That can be ordered here:

This video may help too for the adjustment of the backband style seat. 

Hope this helps and let us know if you have any other questions, 

Thanks