As was said. It is impossible to legally change the tow rating of your vehicle no matter what. If you want to be legal get a 3500 with an Aisin transmission and call it a day.

If you are not worried about the numbers then I would just hook up the trailer and see how it does. If there is too much squat add airbags. If it feels low on power re-gear. Re gearing will help you transmission survive as well at higher loads. If you don't re-gear then at least lock out 6th gear when towing.

I would not suggest towing with any added power due to transmission concerns. If you delete just tow in the 30hp tune.
I'd just leave the transmission alone for now unless it starts to give you trouble. If you have the money laying around an upgraded valve body from Revmax would be a good investment to easily eliminate some of the most obvious weak points. At least some of the overdrive clutch failures that are so common are due to crossleaks in the valve body causing the overdrive clutches to be partially engaged when they shouldn't be. These failures will occur even at stock power levels.