I have the same dilemma,a 2WD dually and finding the right tire combination.I have Cooper AT-3's all around now and they do good on the highway but in the snow and ice,they sucked big time with the camper on.I took them down to Les Schwabs and had them sipe them aggressively..What a huge difference on snow and ice..They wear wonderfully..
Only time will tell how the siping will effect tire life.I had planned on getting different tires for the rear and using the ones I have to rotate out on the front as you mentioned, once these ran out but since the siping,I am happy with the results that I need for my type of driving with the camper on.
I Was thinking of putting aggressive tires(M&S) on the rear and standard type in the front as they have done for years on 2WD trucks but isn't cool anymore for some reason..
Now it is just wait and see how they wear being aggressively siped.Might end up staying with the AT-3 super siped if they wear well.