Swap your bike's shocks for a take-off pair from an I/S.
I'm about 240 at the moment and have had a 200lb passenger plus full saddlebags/trunk on my Tourer and never had an issue with bottoming the shocks out. Ditto when running the Interstates with their stock shock setups and heavier passengers.
Yep, what Bagger said. The quickest and easiest upgrade would be IS shocks, which is what I've done with good results.