I have full skids and an ARB and have never experienced overheating problems. Sliderz seem like the best upgrade after tires.
BTW, have you considered that it's your tires that are causing problems? You said you ran "cheaper" Maxis Mudders (I can't even find that tire on the web
) The cheaper tires might have skimped on the side walls and are causing you problems. I've run Pirelli Scorpions at 9psi in the snow and then ended up on dirt and rock and didn't have any problems even after torquing on them in a rather difficult spot.