If your leveling kit is being used with the stock coils, then yes you can replace the stock coils with TUFTRUCK coils and use that with your leveling kit. But if the leveling kit has it’s own coils then you can’t use TUFTRUCK coils.
Yes, both of them will help significantly when towing, but keep in mind they won’t keep the backend level. With the tongue weight of the trailer, the back end will drop.
The TTC-1223V is a variable rate coil so, if it were to be used for towing, the back end would drop two inches before the second stage started to work.
It’s related to the design of our coils. We have to use thicker coil wire to make them heavy duty and if we made them to OEM height, then the truck would sit too high.