I can see this as being a fun sort of mini-game at the table, with a series of desert tiles/hexes that can be flipped over as the PCs trek through the Desolation to Kendermore. Different routes would have different obstacles, revealed when the PCs land on that tile/hex (or perhaps revealed with a clever ritual or some advance scouting). Not sure how that would work in a pbem game, however.
As is, your setup seems to impact the PCs in one way: how many healing surges they are down when they reach Kendermore. You accomplish this with harsh desert conditions and with what appears abstracted skirmishes with the gnolls. IMO this is a terribly boring consequence, but that's an opinion (happy to discuss it more if you like). The fact is, it doesn't matter how many healin surges they are down if an extended rest awaits them in Kendermore. OTOH if Kendermore thrusts them into a fight as soon as they arrive, then tracking healing surges makes sense.
Some specific feedback...
Traveling during the day is harder than traveling at night with your setup. But I would argue taking a trip through the crags/dried river canyon should be easier with full visibility (I.e. Athletics moderate DC).
What's to prevent a player without healing surges left from sitting out a round?
