I understand the money thing...
...and I know I'll be going against the grain here :roll:
Lots of people lock D35's, and have very good luck doing so. When I got into this recreation, that's mostly what people wheeled; a locked D35 and 31" tires. Where they started breaking things was when they went big tire, and started doing more agressive stuff.
Now at this point, I will mainsteam a bit...
Since you are doing expeditionary things, you may want to consider an axle upgrade, if for no other reason than your piece of mind. It's one thing to snap an axle in an Off-Road park and be inconvenienced, and yet another to snap one in the middle of a desert and be truly F'd.
You could do a Super 35 upgrade and that's expensive unless you can find some used axle shafts. Or either of the two axles previously mentioned in this thread are much stronger than the D35 right out of the box. With an Exploder 8.8" rear, you get rear disc brakes to boot. As you mentioned though, money... For $500-$600 you are locked with a stronger axle.
Either that, or carry a spill kit, 2 quarts of gear lube, and a set of shafts with you.
Your rig, your money. I'm not going to push you either way. I have locked a number of D35's and never saw an incident of breakage where there wasn't real abuse involved. However, the web is full of D35 horror stories...
-Ron