Originally Posted by RedOne
Warn Gen II application for 2009-2011 FORD F-150 4WD (Not compatible with EcoBoost model) looks nice but I can't use it
Yea it looks like your best mounting would be to a trailer hitch, removable winch carrier and a rear battery. It's safer for you and your warranty. You can pull a lot and I would say a 9000 lb would be great back there. A deep cycle battery would run that winch quite a bit before needing a recharge.
It takes a lot of beef to hold a winch in place, don't want to break the front of your truck and the trailer tow would be mounted into the frame and support a lot of pull. Normally a good winch mounting weighs 150 lbs and another 100lbs with the winch.
Adding a trailer mount in the bed would be a great way to stow it with a lock through it for safe keeping. You could bolt down steel tubing to slide it into.