How much trailer can the new 1/2 ton trucks tow?

You can take a half ton and make it pretty stable, which I've done a couple times, but I still wouldn't go over about 8000 lbs loaded. Since you are new to RVing, you would probably benefit from selecting a shorter trailer for your first go around. A 26 - 28 foot trailer can be reasonably roomy, while still fitting in most parks, and be easier to tow than something longer and heavier.