Resource management is a good LTR tension-builder, but it needs to be easier than "how many pounds of food does a human eat?" in order to be efficiently useful.
In 4e, I might use healing surges. If you take an Extended Rest in a "harsh environment" (one where you can't easily access food, water or shelter, or one where hazardous weather is striking), you gain 1 less healing surge, cumulatively (so after 2 "days" of travel, you're down 2 healing surges). A difficult Nature or Endurance check might allow you to lessen the effect (for yourself or others), taking a day or two off it, but the DC's should be climbing every day (begin at 20, maybe +2 or +5 per day, depending on how harsh the environment is). Proper equipment might give you bonuses to the check.
In environments that aren't harsh, "taking 10" with someone trained in Nature or Endurance is enough, so I wouldn't worry about passively doing it. Assume it is done. I guess if the party doesn't have anyone trained in any of those skills, maybe it would be a problem?
The Dark Sun "survival days" mechanic isn't bad at all, but survival days are cheap and the consequences (a slight chance to get "sun sickness") aren't too severe and can be a pain to track. IMO, there needs to be more at stake then some floating -2 penalties if you travel during the day as a consequence for running out of food and water. To be fair, you can die from Sun Sickness...but there's every chance to avoid that fate.