The lift raises the truck center of gravity, so it's more "top heavy" now.
Add the longer drop shank, it's going to add additional leverage to the hitch and the truck.
Just like using a longer crow bar compared to a shorter one.
I'm not saying you can't tow "anything", but you really can't go by the "tow rating" even if you didn't mod the truck... The "tow rating" does not always mean a full size TT... It could be any kind of trailer.
Anyway, I hear what you are saying and you are learning for sure..
Some of us just had to learn the old fashioned way... Before there was this interweb thing and keyboard commandos everywhere, it was all trial and error and what experience we picked up along the way..
Good luck with whatever you decide to do!
Mitch