Is there a rule of thumb for what to set the rear shocks on? With just me, its ok. But add the girl and we hit bottom once in a while. Is there a rule like
300lbs = set on 3
350lbs = set on 4

Or what? She isnt that big but I'm 250lbs.

 

Not sure what you're riding, but I have mine set on 2, for just me. All the way up riding with a passenger.

Rear tire pressure should be increased to 40lb, for 2-up as well.

Check your manual for specifics.

 

I adjust my rear shocks to the fronts, since the fronts are not adjustable. When I am riding and hit a dip in the road you will want your front and back to react the same. If the rear is too stiff the front will, for lack of a better term, act like a pogo stick. The rear will force more wieght transfer to the front and make it bouncy and feel a little on the uncontrolled side.
When you go over the dip in the road at a higher speed adjust the back shocks to go down at the same time as the front shocks.
It is easy to see and feel once you pay attention to what is happening. I am 200# and set my rears on #3. If my whif is with me I go to #4 on my SE FatBob.

If you think you are in between numbers on the rear then go to the softer setting for better control.

Hope this helps
Gutter man