The plug boots on the coil packs go bad they can be changed. They will not give a code when bad. Have been driving only Fords for over 30 years. Changed many plug boots they do not cost very much, and are most of time the only problem not the coil packs or the plugs.
You can use spray lube I lube mine every few months makes a big difference. Leave the hitch in the closed position on a Husky 16k with J jaw when loading just make sure lock is open and pin is out. You only have to open jaw if you have the Husky 16kS with the straight bar. Check this website http://www.huskytow.com/
I have a Husky 16K with a single J jaw. On ours you just make sure the lock pin is pulled and back in with the jaw closed the handle will push out and back when locked. Check your owners manual for correct use. Only time you pull handle is to unload the trailer.
Just remember with 12 volt batteries two in parallel is 12 volts and two batteries is series is 24 volts. I do not think the Cat C7 engine has a 24 volt starter. It might I would check with a CAT dealer.