1) If you require a planted rear-end, you shouldn't drive a pickup.
2) Slow down
3) Reduce air pressure
If you don't like the above, learn to live with a loose rear end.
4) Don't react to the stepping out and the truck will sort itself out just fine. Most crashes are caused by drivers overreacting, not under-reacting. This is a stable truck and it wants to go straight if you let it. Learn to trust the truck and these minor steps-out will stop bothering you. They are only an issue if you make them an issue.
5) Learn to drive a vehicle with a loose rear end and embrace the oversteer. If you really get on it, it only takes small inputs of counter steer to correct a minor slide and it is a ton of fun driving with the rear end leading the turn-in.