dd.stevenson
Super KY
Give 'em a staff of reincarnation with any number of charges. That'll learn 'em.
I suggest you figure out what you are really trying to accomplish. You have a set of contradictory requirements. Gritty, but PC'S are plot immune (to death at least)? 1st or 2nd level for an extended time, but you don't want to fudge die rolls? None of this make any sense.
As best I can tell, what you want is a campaign that is "carebear"* mechanically, but gritty/creepy thematically/tone-wise. This isn't impossible, but requires quality dming and total roleplay buy-in from the players.
My best advice is to greatly lessen the role combat plays in the campaign. Use/build npcs/monsters that do flat damage instead of die rolls; this removes fudging, builds tension throughout as the players know exactly how many more hits they can take, and removes 1 shot potential. Reduce natural, non-magical healing... but give ample, but not guaranteed, downtime between encounters.
So the only real trouble is finding out what my best options are for dealing with that one "sensitive" spot (levels 1-2ish). It's going to be an extended period of time, and I want to provide just the right amount of options for dealing with the possibility of character death to keep from falling back on the more extreme options I have available too early in the characters' careers.
I don't understand the dilemma here. You've purposefully made it more difficult to raise the dead. I assume this is to make it gritty and make death matter. And I get that, it builds suspends. Heck, you could even remove resurrection entirely if you want.
And yet you want a safety net? You want no safety net, but you want a safety net? Make up your mind.
If you want to run a campaign that doesn't hold any punches, then don't hold any punches. If they die, they're dead, end of story. Tough luck, make a new character.