I do agree a wdh is best preferably something with sway control....ford usually requires a WDH for anything over 500lbs tongue weight. Your tongue weight will be around 12% of your trailers gross weight not what the brochure states. That is the dry weight with nothing in it and no battery.
To answer your question you will want the ball 1-2in above the height of your leveled trailer. The end goal is both truck and trailer are level and neither is propper up or down. The distance of 1-2in will depends on how much squat you have on the tow vehicle. If the front end pops up you need a WDH and maybe even if it does not. If you are not sure of a type check out etrailer.com and provide your TV info to get some options.