Re: Deathclaws, one thing that makes them somewhat easier is that they are generally compacted to a few areas in FO3 and NV. You can more or less find them and nope the fuck out until you're high level. And when you engage them you can hulk out on chems. In my playthrough it was impossible to just stealth-snipe them, but you could position yourself such that once you opened with stealth-snipe you'd have enough time if you shot them quickly to kill or injure them enough before the rape train of death claws caught you.
The next east of
Techatticup mine - The Fallout wiki - Fallout: New Vegas and more - Wikiaacross the Colorado River has a massive nest of them. Much bigger than the quarry. It was really tough taking them all out.
But to the previous point, I don't think it'd be possible to kill them without stealth and sniper rifles at the difficulty I played at and with the mods that made them harder.