120 is fine, and even then you can easly roll around wasteland with 20 outdoorsman and not die, its just annoyingly many encounters and slow speed.
My current bomber alt now 5th level with 28% outdoorsman has more chance to avoid encounters than 21st level main with 120% outdoorsman, and even have more XP, probably because of level, but may be because of low outdoorsman too.
No, 120% isn't fine, you shouldn't raise outdoorsman at all, or raise it to 200% and be taxi alt. Because I don't see any difference between:
have 28% outdoorsman and run away to exit grid each encounter on RT.
and
have 120% outdoorsman and run away to exit grid each encounter on RT.