Advice needed -- will I regret a shortbed w/ 43' trailer?

Instead of using the listed dry weight of your trailer, find the GVWR of the trailer. That will give you a more realistic picture of what you should buy to tow it. Most people use 15% - 20% of that GVWR to determine the hitch weight. A Dodge 3500 should have no problem pulling that BUT the limiting factor is usually payload of the truck. If you're near max weight of the truck when you get all your stuff and people in it, then add 1500lbs on the hitch, you could go over the truck's GVWR.