I am interested in how you play your gritty campaign, what optional rules you have, what options or rules worked, what didn't.
Oriaxx
One thing I learned while surfing the messageboards is that "gritty" doesn't not necessarily means the same for everyone. For some, it's simply about the state of the world, for others, it's about low-resource management, for others, it's about the high probability of death, or dismemberment, or lasting consequences of injuries, or emphasizing on "mundane" factors such as weather, exhaustion, disease etc. so assuming you mean a bit of everything...
A gritty campaign is principally in the way the DM runs it, and describes it. Still, it works best when the rules support the theme, or at the very least, don't go against it. Your blog already mention a few.
IMO, a less generous rest mechanics is required. The DMG proposes the "gritty realism" variant, which is a good start. One needs to be careful however, that variant does not make anything "grittier" or more "realistic", all it does is stretch the adventuring day over an adventuring week. Still, a good start, but any rest variant that translates in "adventurers are not fresh as a rose after 8 hours of crappy camping" will do. Longer refresh time on spell slots also put an acceptable break on the "magic is the solution to every problem" element of D&D.
The "threat" of the mundane world needs to be significant enough to deter players from ignoring it. In D&D (across pretty much every edition), a high level character has little to fear against the 20 king's guards that have come to arrest him/her. Or just cold, wet rain. Or the steep ascension between this town and the next. Or wading through snow, or any type of difficult terrain, even if the temperature are mild. Not to mention food and water. The easiest way to convey that is to keep the characters at low levels (like 1-5, mayyyybe 1-7). The problem with that is often about player satisfaction; they have the impression that they are playing only 1/4 of the game (not without reason). Otherwise you can re-write the NPC blocks, but it will still be a problem once the characters get to level 11+.
HP work well as an abstract health bar, but it doesn't represent injuries well. The spiral of death is somewhat of a slippery slope; you need it for grittiness, but it can cause rapidly degenerating conditions that can frustrate players. Of all the houserules, any type of death spiral is the one that moves the game experience the furthest from "vanilla" D&D. Personally, I like the "one exhaustion level when dropped to 0-hp, which disappears when character is brought back to full hp" rule. I also heard of "exhaustion levels as death saves" but never experienced it. Exhaustion levels are VERY punishing, but so should be gritty combat.
About that, I've toyed with injury (resulting in exhaustion level) on receiving crit and rolling 1 on save or ability check made to avoid damage, but it was a bit too much. Put that in the "what didn't work" bin.
This brings me to exhaustion; physical and psychological fatigue is an important part of grittiness. You can deal with it naratively, but 5e does have a mechanical representation for it. Difficult travel, forced march, harsh weather, prolonged stress and tension, antagonistic social situations; all have the potential to cause exhaustion levels and should be enforced by the DM. You can add mental and social situations to add the potential for WIS or CHA saves vs exhaustion too. I considered adding a "winded" level-0 exhaustion level with no drawback, primarily serving as a warning in long rest = 1 week games.
So in my personal and anecdotal experience: you can't represent a gritty setting perfectly with 5e rules, but you can get pretty close. As you say, the players need to be on board with it because it will feel very different. Beyond the feeling that the king's guards will always be stronger than you, players need to be ok with the definition of heroism not as slaying dragons, but as being pressing forward despite the exhaustion levels, the partial hit points, the limited assortment of spell slots, and the low resources. This change in paradigm is the biggest "what didn't work" I've encountered. Sometimes players just want to slay dragons, and that's cool with me.
'findel