I've been looking into lowering my 4th gen, 2016, quad cab 2/4. I currently have Bilsteins 5100 in the front and stock in the rear but would like to get 5100s in the rear also. There is a McGaughy's 44052 (for quad and crew cabs) economy kit, which allows you to retain your factor size shocks, and includes the panhard bar relocator bracket. I also have the Airlift 1000HD bags. Currently these are installed in 2in rear drop springs, MaxTrac, which gave about a 1 and 5/8ths inch drop in the rear. For me this is appears to be my best option to keep stock size shocks and possibly will allow me to use my 1000HD AirLift bags.
Depending on if this bottoms out on the bump stomps, I will then go the Timber Grove option. I do haul large paylods (up to 2400lbs max) and also tow a 20ft travel trailer at times.
This may not answer your question with your regular cab, but I think it may be a place to start you search. I think airbags in the rear is the way to go, either working with the springs or replacing the springs altogether with airbags. Timber Grove has some solid products.
