Ford 2005 spec here: http://www.fleet.ford.com/resources/...wing_Guide.pdf
FX4 Ranger models have less towing weight rating, as do Manual transmission vehicles
Safely and legally can be different, like "can it" or "may it"
You "can" exceed Fords recommended Safety towing weights, BUT.........if there is ever an accident, even if it had nothing to do with weight, insurance companies can bail out on the "operating an unsafe vehicle" clause, that is the "may not" side, legalese.
Surge brakes work fine for most trailers, these are on the trailers tongue, when you are pulling on the trailer the brakes are off, when you slow down, or use the brakes, the trailers weight pushes against the tongue which applies the trailers brakes.
Electric trailer brakes do require a controller to be installed in the cab, and are required in some states when a trailers weight exceeds XXXX pounds loaded, so check your states regulations.