Good to know that you use only one diff, maybe others will soon too get the point.
There may be other ways for traction but I cannot figure anything cheaper/simpler. Lift switch should be inside cab so that you could lift while driving if the situation demands it. There's also no reason to roll tag axle tires when empty.
Electric water pump would be ideal since your truck is not going to need half as much cooling than the standard truck water pump is designed to give. And if you use, for example, evans coolant, I think you can keep the motor at least 10 C hotter than usual anyway without worrying about boiling.
Also, I think you should visit rvs-tec website.
Even though it sounds like science fiction, it does work as it is advertised. I think you will find multiple places to use RVS. Engine, transmission, differential, wheel bearings...