The Rear Mount cargo system is connectible to any surface, top, bottom, front, side, back. However you feel it will work out with regards to your bikes center of gravity.
The pannier mount system when mounted on the front of the pannier uniquely sits on the passenger foot peg. This transfers the weight to the frame instead of torquing on the pannier and eventually cracking it out after miles of washboard roads. It is possible to mount two one gallon rotopax cans per side. Using the forward side pannier cargo mount also keeps the center of gravity forward.
We designed it to work on a BMW pannier and still be able to access the latch.