Losing and regaining grip or clutch dumps on dry surfaces and it not spinning the tires is going to be what will break axle shafts. That can be as simple as not dumping the clutch when it’s dry and if you’re in a situation where you lose grip, lift off the gas. Don’t stay in it because that’ll be extra shock when the tires hook up again.
If you drive smart, the D35 will live. Between me and my parents, 5 out of our 6 D35s have survived abuse and clutch dumps. The 6th one was an AMC 15 (Dana later bought this design and called it the 35) and was behind an auto, but had 2 piece axle shafts and the spines where the two pieces meet stripped out. I have another D35 with a locker that was on a lifted XJ with 4:10s and survived, but I haven’t run it at all.
If you’re worried about it, find a different component to be your weak link. In the case of our Jeeps, the tires were always the weak link. They’d break loose before the axle would break. Unless you’re dead set on 31x10.50R15s, it might be worth looking into 30x9.50R15 tires or even stick with 235/75R15s. The smaller contact patch will perform better in the snow and it will hopefully break loose on dry pavement before damage occurs. You don’t need huge tires or lockers to be able to play off road. I wish I learned that earlier because it can save a lot of time and money. That said, there’s nothing wrong with having big tires because they look cool.
Or consider the tire compound. Maybe look at a tire that’s designed more for road use than for trail use. A more road friendly tire will most likely have a harder compound and spin easier than a more aggressive off road tire.