I have been testing this for a while just to be sure.
With my present PC who is a decent level druid, has 10 on the EFUSS Survival skill and trying to sleep in the Steward HQ, which is "teeming with life", in testing he has a 50/50 chance of resting without food.
This roughly 50/50 chance is replicated across the other wilderness areas.
I think with 10 in Survival and being a decent level druid/ranger/barbarian you should have a far higher likelihood of making the successful roll.