If most of the teams are driving with locked hubs you may want to think about disconnecting and plugging the vacuum line to the hubs. This would prevent a bad seal from sucking the "moon dust" into the needle bearings and destroying them. Of course you would have to make a warning sticker or sign for the dash letting the driver know that the ESOF would only operate the transfer case and that the hubs must be left in the lock position for four wheel drive.

I am in the middle of doing the servicing on the front hubs on my truck and I can tell you it's not a quick job. Some of that is dealing with the rust that likes to hold things stuck together. I have one side done but have to replace the knuckle seal on the other side. I'm really looking forward to doing that tomorrow in the snow we're supposed to get...

Oh yeah, that reminds me. Keep the caliper slide pins lubed up real good, it will save you some trouble down the road along with brake pads and/or rotors. In the conditions those trucks will be operating in, popping the caliper off and giving the pins a quick cleaning and a fresh shot of grease when you have the wheels off can't add more than maybe half an hour to the job and might be worth considering.