As you noticed many feel the trailer is too heavy for a light truck like the f150. A lot of these guys have been in the same situation as you and ended up changing trucks or trailers because they didn't feel safe towing. You have towing experience so I'll recommend hitching up and giving it a try before you buy and get the feel for yourself. Some RV dealers are ok with it some are not but if it's a private seller I'd say mandatory. You could head over to the Ford truck forums and ask the same question, you will most likely get more response from those with the same exact truck. I think the web site is Ford-trucks.com