Tire ply --6, 8, or 10 ply Help
All good information so far. I have the 2013 version of your truck.
A word of caution to you, the tow package you mention is the limited version, don't confuse it with the max tow, that would change the suspension and eliminate the Z71. The caution is that the Z71 is for a softer suspension, for off road use, thus it will be more susceptible to induced sway, so you will want to go with stronger sidewall tires to compensate for it and the suspension will eat up the roughness.
Mine has the max tow, Z82 suspension, rides somewhat stiffer so I went with some Goodyear Eagle Sport V rated XL tires (over 2500 lbs each derated) (it's not really a winter truck) both our trucks have a GVWR of 7000 or 7600, so any of the recommendations you've been given are strong enough to carry the load, but the Defender "E" tires are probably your best bet.
But definitely get rid of the Goodyear's it comes with, they are complete crap for towing.