No, it's perfectly normal for a 1/2 ton truck to be on the bump stops at max payload. That's how they're designed.
The best thing to do is take it to a spring shop and have them recurve your stock springs back to stock, and add a leaf or two. It will be the strongest modification.
Really the choices are endless and there are no wrong answers to this. There are many home-installed "helper spring" style products on the market that all do the same thing in pretty much the same way.
Don't forget your tires. They have actual weight ratings written on them and you'd better adhere to them because when they say XXXXlbs, they mean XXXXlbs. You'd probably be best off upgrading to an LT type tire with a heavier load rating.
