Jeff; Overload springs should help without lifting the truck. Lifting raises the height but may not help with the load capacity. Hellwig makes overlaod springs for small trucks, one source is here.
http://www.suspensionconnection.com/...helper_springs
Supersprings also makes overload springs. A source for them is;
http://www.loadandtow.com/
I believe the Supersprings for 2 wheel drive trucks require cutting the rear bump stops.
I have not tried either of these products and have no experienced with either link, but if I needed to carry heavier loads I would try overload springs before lifting the truck. Lifting can also cause some handling problems.
I noticed JC Whitney have Hellwig products, but you may not save any money due to their high shipping charges.
Clifton