Bilstein 5160 or 5100 rear shocks for lighter constant weight?

My v8 runner has no back seats. I removed them and replaced with plywood/carpet. I'm probably 100 lbs lighter than stock weight. I mostly street/highway drive. No wheeling. I currently have 5100's in the rear, but they are dead now (8 years old!), and I need to buy new shocks very soon. It's my understanding that having the beefier 5160's without constant extra weight might ride like pooo. Is this true? Or might the 5160's ride just fine even with my Runner being lighter in weight? Anyone experienced with this? Thoughts are welcomed.