Short answer is No. But is it possible? Yes, but why risk it. If I were in your shoes just moments away from retirement why would I want to create new problems/risks. I would get an F350 or equivalent other brand and be done. Especially if you upgrade to a heavier fiver you'll be set. A 1/2 ton is far too inefficient. Based on where I live and often travel an F150 would just choke and puke all over itself after a short time and or it would land me in a ditch or wrapped around a tree. Tow power is one thing but handling, stability and braking power are critically important and no freakin way I'd want to be going down a 8% grade in a 1/2 ton. So if you like livin on the edge then go with a 1/2 ton.
Also, if you're just a few lbs overweight and you get in an accident (regardless of who was at fault) and the insurance party finds out you can kiss your retirement dreams goodbye. I mention this because I seen it happen. Very sad.
http://fifthwheelst.com/before_you_buy.htm
http://rvingwithmarkpolk.com/2012/03/21/caution-why-truck-tow-ratings-dont-add-up/