Hi asndy,
I recently bought a large belt from GG for $20 that almost fit my Mariposa Plus. I had to do a little ripping and a little sewing but essentially the stays werere perfectly spaced to fit into my old pack.
This made a huge difference with the staays now grounded to the hipbelt.I will be using the pack a whole lot more than i have.
BTW its the large belt for newer than 2011 packs. I think I got my pack in 2102.
TomL