What Grog and Tbone said.
Towing that much weight with a half ton truck or SUV is inviting trans and diff failure, if not immediate, certainly down the road. They are not built heavy duty enough to handle that much weight. As mentioned, for down the block to launch, may be ok, but over the road a 3/4 truck is the way to go.
Aluminum bunk trailers are very popular and save quite a bit of weight over a galvanized steel. The Kodiak brakes are far superior to Tie-Down, I have the latter, I know. Magic-Tilt are a big name, I have a Road King, they are also good trailers. There are several brands out there, get one from a local dealer that can set it up for your boat - will save you some headache.
The diesel trucks get much better fuel economy than gas, and have a lot more torque for pulling. But they cost more to buy. With the economy values are way down. You can get a nice Duramax right now for well under $20G's, and they have the Allison trans which is the best available. The only thing good on the Dodge is the motor, it's great, the rest of the truck sucks (did I really say that? :shock: )and the values are way low. The older big-block Powerstrokes are also good. There are some steal-deals on 3/4 ton 'burbs right now too, make a great cheap tow rig.