Personally, I wouldn't trust bumper hitches to tow over 3000lbs. A bumper hitch is more for towing very light trailers, or ones that don't require a braking system. Depending on the state, or your area, a trailer brake is required over a certain trailer gross weight rating. As mentioned, most bumpers can easily tow upwards of 5000lbs, but you'll get better stability with a hitch as it's mounted lower (on the vehicle frame). If your F150 is anything like my old GMC C1500, the bumper hitch is actually attached to the box with a steel crossmember. It's NOT attached to the frame. So the weight went through the bumper, on the box, and then onto the frame.
If you're unsure of your axle ratio, check in the glovebox, it should list what the ratio is on a sticker, and whether or not you have a limited slip axle (better on boat ramps but not necessary; it eliminates the one-wheel-peel).
Boats are almost as aerodynamic as a landscape trailer, and don't have the drag associated with say, a travel trailer for instance. Towing at the limit of 5,200lbs is more than doable with the V6 as it has good low end torque. Just remember to factor in other weight as well, such as passengers, driver and cargo, and subtract that from the towing capacity. In any case, providing the grades won't be overly steep, you have the shorter axle ratio, and a transmission cooler installed (for automatic), a 4,800# boat would easily be towable, but you'll have NO passing power unless driving downhill, in any case I'd advise against overspeeding the vehicle. If automatic, tow in 3rd gear (1:1) and don't exceed 60mph for best long term reliability. If manual, tow in 4th and don't exceed 65mph for best long term reliability.
'11 Ram Quad Cab 4x4 SXT 5.7L HEMI (stock); 48,500m
'06 Pontiac G6 GT 3.5L 220hp; 64,000m
'12 Chrysler 200 Limited 3.6L 283hp; 28,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!