need Tow Vehicle

I bought a used 2000 durango to pull my boat (about 5000lbs) but it only had a 4.7 in it, and it cannot pull the boat for more than 15 minutes. Now I am looking at a 2007dodge ram w/hemi 40,000 miles or less for $17,000. Is there anything better? I think the diesels cost too much and I only need to pull 5,000. I know the hemi can tow it for a several hour trips plus get 20mpg when not in tow, so is this the way to go? It does have to be an extended cab and 4x4. The dodge is the only truck that I have experience in towing, so please let me know what vehicle you have towed your boat for long distances and has worked for you.