If the GW is over 3500lbs, it is required to have brakes here in VA. The tongue weight may cause the 1/2 truck to squat quite a bit---even perhaps dragging the hitch on the road. The helper spring will "help", but, It should still be of a concern even w/ that. Any chance you can put air shocks on it? Pump it up to about 170 lbs psi and she won't squat. This isn't a long term remedy of course.
I would be concerned about the 4.8 litre as well. You must have a tranny cooler if it is an automatic.