I've ran overloaded pickup trucks for years. For a few generations of trucks now- pick a brand- the differences between 3/4 and one ton trucks is generally minimal. The single biggest difference is in the springs that are used. Unless your talking a dually....then throw my statement out the window. So what's safe? You can put bigger springs on, add air bags, sway bars, pay close attention to where weight is located (high, low, front, back,etc....) I know from a lot of real world experience that you can make many substantial improvements to a truck to help it carry a very large load better. My personal test....how does it drive? Does it drift? Does it chase dips on the road? Does it pull grades well? Does it stop? Does it stop well. If you can comfortably say yes to all these then you could rationally say "this is ok" However- if you get in a wreck and hurt someone....and your overweight to what the trucks manufacture says- it's not good. And it's going to be awful to live with if you could have prevented it. It's a risk. I drive with extreme caution if I'm overweight. Generally I don't do it as much any more. Wisdom comes in many forms. I hope you can find the wisdom you need to make a reasonable decision that works for you. You're certainly in a good place to seek some good input from a great group of people. Good luck.