Beware if you're towing in hill country with a half ton. I'm not saying it cant be done- far from it. But half tons, bumper pull trailers and hills are a great way to end up in a bind.
Like others have said- air bags, a brake controller and an equalizing hitch will go a long ways towards keeping you safe.
Having said that, if you're looking for a new pickup I'd go gasser if you're only towing occasionally.
I've had several diesels and they're awesome if you tow alot but they are expensive to buy, expensive to maintain, and can be a pain in the ass in cold weather.
And I would 1000% stay away from anything that requires DEF.
Good luck in your search!