Here is my 2003 2500HD with my Bigfoot, which is about 3300 lbs all loaded up. I added one leaf to each spring pack and made my own stable loads that I could install just before loading the camper. I used Bilstein blue and yellow shocks (highly recommend these). Tires are 26/75r16 E Toyo open country HT tuff duty which are rated for 3417 lbs. Ran this set up for two years without any problems before getting a set of 19.5's... I guess we get a little funny as we get older.
My stable loads... Used a pry bar to move the overload spring down so I could slip in my spacers, then bolt them up.
Here is a pick with the 19.5's
