I dont like the idea of timer for resting ... for several reasons ...
But i gues some restriction here is in order ... i allready heared that people should be able to camp only from "safe" areas ... wich seem interesting.
But if there should be some "timer" i will certainly not tie it with real time ... how about you just "fill" some imaginary "rest metter" with everything you do ... exploring and talking give you small portion of this metter, on the other hand combat gives you much much more.
Lets say you should be able to rest every 1-3 easy combat scenarios for example (those are combats like in Blighted Villiage, where you have potentialy 4 groups of goblins) or one hard combat (practicly every encounter in underdark).
The OP made good point that players should not expect to go to sleep 10 minutes after wake up ... but when you realize that the ratio between real and game time isnt 1:1 ... and also you realize that your character was just fighting the whole gnoll pack, or whole goblin camp ... it starts to make sence they are exhausted even after 10 minutes of play.
