

I wonder if this kind of arrangement would help? Never had a sportbike but I recall friend’s GSX-R had a removable passenger seat. Pop it off, lay two straps like this so that they end up behind some studs or latches so they can’t fall out. Then the seat goes on top.
There are stubby figure 8 knots on doubled up sections of the strap so that a loop is formed. Then strap bags onto those loops. The length of the straight portion of the strap should be exactly the width of the seat so the loops and knots peek out at the edge of the seat.
I don’t know if there is a search term, it’s my as yet unnamed invention 😄