Either cut a coil out of the front or change the springs out for 2500 hemi springs. For the rear remove the three spacer plates in the bottom of leaf spring pack or remove a leaf spring or two and add helper bags. Heck just 4 link the rear and air bag it! Bolt-On 4-Links :: HD 4-Link - RideTech.com - Suspension Specialist - Online Store
I know people that tow with the overload and two of the plates under it removed, the third one stays for the alignment pin, with air helpers. That would drop the rear about another 2".