Very true about the marginal TVs.
I highly recommend anybody looking to tow a travel trailer plug all the relevant numbers into the ever so handy PUX Towing Capacity Worksheet.
http://www.popupexplorer.com/resources/resources.php
This thing takes into account everything, and you'll know for sure where you stand w/ the trailer you are looking at. Obviously not you as you have a F250 towing a 5k pound camper !!!