Why not give new Gangplank a jungle option?
Alright. A looooong time ago, Statikk had mentioned he was interested in the prospect of working a jungle option into the upcoming Gangplank rework. Tried to find it, but it was in like, 2013.
After his first rework, featuring his new stacking passive, Gangplank saw use in the jungle and was pretty powerful, used to great effect by M5 at the time, and other teams. Ultimately, this was changed, as he was very difficult to get away from with red + passive and it was considered 'toxic'.
Now, with his recent rework, we find that he is designed exclusively as a solo-laner. His passive is no longer applied by Parrrley (which is a cool design decision and rewards melee play), while Parrrley retains it's on hit effect abilities. I feel that if, either in his passive, or his barrels, he was given tools to clear the jungle, he wouldn't necessarily be super overpowered in the jungle. His ganks would require Parrrley redbuff and getting into melee range, OR using awesome barrel setups in lane-ganks.
It wouldn't be too hard to accomplish, either. You could bake extra monster damage into either his passive, or his barrels, giving him the ability to clear. He's a dangerous duelist, and I feel that barrels are SUPER cool in jungle environments where vision is limited and it would require enemies to be aware of potential powder keg setups out of vision.
The tradeoff, of course, is that he would farm his ultimate and gold slower, and his ganks would be weaker compared to other junglers.
I dunno, this is just food for though. Old Jungle GP was my favourite build, even if it was bad, and one thing I really support is champs that can fill multiple roles.