steved,
You may already know this, but keep in mind that the receiver is just one link of the tow equipment. Even if you go to a "true" class V receiver it won't matter if the ball mount and ball are only rated for 5K. Like you, most of us have towed at the max (or slightly above) for what the stock receiver is rated at from Dodge; whether we are set up or not set up with W/D. However, if you don't want to go to a true class V rec'vr, I wouldn't tow that load for that many miles without the W/D set up.
Here's my short story made long:
Not too long ago the wife was giving me grief because I wanted to tow our 31ft, 7500lb trailer to the dealer approx. 25 miles away. I had lost the W/D ball mount (that's what happens when you forget to put the pin in

) and I was going to use a standard ball mount with the 2 5/16" ball. Even though I was comfortable towing it for that short distance, she put up such as fuss. so I said, "fine!, if this isn't good enough..... guess what? the stock receiver is only rated at 5,000 lbs without the W/D and I can't tow a 7,500lb trailer with it. " I went with Putnam because I couldn't find another class V receiver with a 1,500lb/15k (wgt carrying) and 1,600lb/16K (wgt distr. ) out there.
Like I said, the rec'vr is just one link. It doesn't do any good to have a rec'vr rated at 15K if the ball mount (and ball) is only rated at 6K. Putnam makes ball mounts rated for their class V rec'vrs. I opted for the adjustable 2 5/16 ball and pintle set up that's rated at 1,600lbs/16K so I don't ever have to think about my weight if I don't want to..... even if I'm not set up with W/D. Most places that sell tow hitches, only sell balls rated at 5K (6K, tops). Go to an RV place and you can get them rated at 10K. But again, if the ball mount is only good for 6K..... that'll be your weak link.
I found my set up at:
http://www.hitchesonline.com/
They were the cheapest and had great customer service. The site doesn't list a Putnam class V "XDR" for an '04 or '05, but I know Putnam has one (you can go to their website). The Putnam p/n is 25211 for a class V "XDR". You could call "hitchesonline" and ask him to order that part number.