My 12 Ram CTD came with the same pre/post tow requirements. I got about 480 miles on before towing but didn't follow the 50 mph rule. I was heading to the mtns so I was on a 55mph posted hwy. I just ran the posted speeds and since there were corners and such my speed varied enough to not worry.
That 50 mph break-in requirement is ridiculous if you're on the interstate. I live in Oregon and I can't imagine driving to say San Francisco Ca at 50 mph.
I certainly wouldn't run 65mph down the interstate after the initial 500 pre tow break in, but 55-60mph seems reasonable.
I'd like to know where these manufacturers think you can drive 50mph for 500 miles while towing.