Having a passenger for many miles over the years my opinion is the shocks and springs rates on the standard were a bit weak. I went with the IS schlock /spring and have been very satisfied. Progressives as well would be an improvement.
I built a TourerState for Blondie back in the day (which is mine now) and one of the first things I did was to get a set of I/S shocks on it.
It has an I/S trunk, I/S tank/radiator/radiator pods, front fender and fork deflectors. The other thing I did with this one is installed Hyperpro fork springs and 15wt fork oil but kept the Tourer damper assembly.
I'm around 240 at the moment and my co-rider varies from 160 to 180, depending on how well she attacks her homemade Christmas cookies. We both like the ride with this setup.