I've been testing if Bounty Hunter is required for 100% Completion. I found today that it is only required to obtain rewards that are obtainable nowhere else in the game. For example the games unlockable cheats.

I tested 4 examples of this and every Bounty I completed had no influence on the games 100% tracker. If a character or level etc is obtainable anywhere in the game and you have purchased or unlocked it in the story, there is no need to complete that characters respected Bounty challenge.

Examples

Professor Perry is unlockable via the "Freak Show" Bounty but is also obtainable by purchasing him in Brimstone 2 at the general store for $666. Item "Monocle"

Natalie is unlockable via the "Saloon Fight" Bounty but is also obtainable by purchasing her in Brimstone 4 at the Clothing store for $1100. Item "Hand Fan"

I've compiled a big list of ways to avoid doing Bountys and will probably post it soon once I've proof checked it all. This also applies to Excellent ratings, but not as many of those are skippable and also, excellent ratings are usually not too difficult to obtain.