Suspension advice needed (I know nothing about cars)

The question: I'd like to know what I should be looking at to replace the stock suspension(springs, shocks, ???). Either comparable or slightly better set up.

The truck: 2005 Access Cab 2WD TRD Off-Road.

The reason: I have been hauling 2 dirtbikes(250's) on bumpy roads lately and the rear is bottoming out. I feel like carrying 2 relatively light bikes should not make this thing bottom out. The bikes combined wet weight is around 500lb, I'm pretty sure I'm below the max payload.

Bonus question: If you are in socal, give me a trustworthy shop.

 

Are you looking to stay stock height? level it out? lift it?

sounds like you might be able to get away with just the factory add-a-leaf unless you want to look into a lifted application

 

second the add a leaf mod, I would just bring it to a local spring shop and let them do it, with their parts.