J.Quondam
CR 1/8
Interesting way to approach it!That's why I prefer to see if a player benefit from a long rest AFTER the long rest.
The players take their long rest, at the end they make a CON ability check against a DC to see it they recover from said rest.
The DC is based on the ''level of comfort/danger'' of the resting place, and you add to that a +1 or +2 for every strenuous activity the character perform during the long rest.
Taking a long rest in the Gloom Forest might be a DC 13, but if the wizard decide to spend 1 hour to look for food, scribe a spell or two, then fend off the were-possum raiding their bags, the DC might amount to a DC 17 or so!
Does the party somehow make the check as a group, or does each PC roll individually (so some might benefit, while others don't)?