Those side panels are big pieces and you do need to remove much of the remaining interior to get them off cleanly. There are some bolts near the seat latch holding the uppper part of the seat steady. I believe those need to be removed. Since the plastic is so big, I found that getting started is the hardest part. I will generally start at the hatch and work my way forward, one attachment point at a time. Once I have one or two disconnected, I can usually reach in and gain better access to where the panel is attached and get it out without damaging the fasteners. Also, from memory I think you can get those white plastic flanged rivet attachment thingys at Autozone if you break one.