Not sure what you have slated budget-wise, but you can get an OBS (old body style) 7.3L Powerstroke CHEAP by diesel standards, on average about 3k for a 4x2 with 200k miles. They're not without their nuances but the engine block itself will last forever and they'll get up to 19mpg in stock trim unloaded, a reprogrammed ECU will yield 21 or more with other mods. You can tow just about anything with it. The ZF-5speed and differential are better than what Dodge offers with the Cummins. The 7.3 is much better than the newer 6.0 from a longevity standpoint, and no emissions crap to worry about.
I've owned my '94.5 (1st year production) for 7 years, it's never left me stranded. I bought it on Ebay from Texas, flew down and drove it home. Sometimes think of upgrading but am unwilling to sell for the going prices. It pulls my 20' enclosed well. The trailer tows like a dream, torsion axles are the way to go. The only thing I have to look out for are semis, the drafts have a tendency to throw me around a bit not an issue with an open trailer.
The only drawback if you're daily driving it would be winter, plugging it in at night is pretty much a necessity if you're keeping it outdoors. Glow plug relays notoriously fail but the glow plugs themselves last.