Hopefully, others that have more experience with a stock setup can chime in.

Since my 4Runner weighs about 500 lbs more than stock, rear shocks that I'm most familiar with will be too stiff for stock 4Runners. So at least I can say Rancho 5000's and OME N86 shocks will be too stiff for stock. Bilsteins will most likely be too stiff as well. OME (Old Man Emu) has a softer version with the model number N86C. That one would work fine for stock, although I've broken off 2 of the top studs of OME N86 shocks and I know 2 other people who have also broken the top studs off of OME's. Now I'm using Rancho, which has a much thicker top stud.

Just in case you're afraid that the shocks will be too soft when towing, you might consider an adjustable shock, such as Rancho 9000 series. I'm sure there's a couple other brands too. Rancho's seem a little bit cheaper build quality in general, but the adjustability can be very nice, so you can turn a dial on the shock to make it softer or firmer depending on your situation that day.