How to increase the payload capacity?

New poster here. Searched the posts and could not find any info on this subject.

I have an 08, DC, TRD Offroad with the rear leaf TSB(everything else is stock). I recently loaded up my truck for a long weekend of camping and climbing. Loaded the truck with a lot of firewood, few coolers, grill, etc. Didn't seem like that much weight to me, yet I was 1" off the bump stops. This is with the rear leaf TSB done.

Does anyone have advice for mods to increase the payload capacity? I don't necessarily want a lift as I don't wheel that much. I just want to be able to load up this truck and run down a bumpy road without riding on the stops.

Thanks for help.

 

I got a dumb question (surprize!) what ever happened to 'air shocks' or 'spring loaded' shocks? Don't they make them for our trucks? I had a KILLER set of air shocks on my '79 Malibu-but that was years ago.

 

Thanks for the advice.