Will this BMW waterproof duffle bag installable on R18 Rear seat?

[firstime911]

Will this BMW waterproof duffle bag installable on R18 Rear seat? I am hoping to mount it on the rear seat, but where to install the all the stripe.

 

[Gilles]

I have the Oxford Heritage roll bag and I slip a strap under the front of the seat and another at the back. I then pass them through the bottom rings of the bag and attach them on each side.
It is very secure.

 

[Black Dog]

Will this BMW waterproof duffle bag installable on R18 Rear seat? I am hoping to mount it on the rear seat, but where to install the all the stripe. View attachment 837

Drill lots of holes and bungy cords, anything will fit.