HELP- Newby in maxxed out Tacoma looking for wisdom

I am an ex moto rider getting into truck camping for the first time. I have a new 2015 Tacoma TRD offRoad access cab with a new loaded four wheel camper and Aluminess Bumpers. I am probably 400 lbs over the max payload for the truck.

In order to support the weight I added a new Helwig rear spring pack (5) and Firestone air bags. I have Cooper Discoverer A/T tires class E.

Ride on paved roads is great. I am currently in Argentina headed south on Route 40 and have several hundred miles more in pretty rough sections. My problem is on rock roads and washboard it way too stiff. It is a teeth rattling and everything else on the truck shakes. I don't want to break anything.

I am hoping that someone knowledgeable with more experience than I have can offer solutions like how much air to run in the tires off road and where to inflate the airbags? If anyone out there has any advice please help me out.

I am totally new to trucks and suspension!