This is a very bad idea.
I won't dwell long on the idea of saving only while resting in a game that is 90% rng based.
However, resting in a given location is pointless because there is a fast travel in the game from anywhere on the map. Changing it to specific places does not make any sense, at most the player will spend 30 seconds to get back to the place.
That way, it might as well stay as is.
Limiting rest to some stage in the story makes even less sense because the game is fully non-linear, which means that the developers are not able to predict in which order the player will fight.
Something like this is turning off the problems.
