Sadras
Legend
This is total off the top of my head, but I think it would be easier to handle this in the XP system. After a long rest, the first encounter is at 50% xp and the second encounter at 75% xp. The fourth encounter after a short rest would be at 125% and +25% per encounter after that. So the party knows it is penalized by frequent long rests. But pushing their luck after a short rest could benefit them. There might be an exception for boss fights after a long rest at the DM's discretion.
After all, XP awards should be adjusted by the actual difficulty of the encounter. While usually that is just a CR kind of thing, there's no reason why a timing element could not be included.
The above is pacing mechanism and doesn't necessarily solve the attrition problem. Players can still go-slow. Two XP proposals were already addressed in the parent thread, one like yours as a pacing mechanism, the other utilising XP earned (separate pool) during the adventuring day to 'buy' (gain) rests.