I was a little disappointed that Stronghold Kegs are limited to strongholds even if the name implies it. They are worth far more than I was expecting which justifies it slightly however I'd still love to see more opportunities to get one of these chests.
I think gunpowder skeletons are the perfect fit as they most certainly don't guarantee a reward. It's a tricky scenario trying to steal a skeletons keg made all the more intense knowing if you mess up then not only will you die but you'll lose a considerable amount of money. #PiratePriorities
Of course this should be a considerably rare occurrence and the skeletons should not ignite the keg from a further distance but I think it would be a great addition to both Shrouded Spoils content and Gunpowder Skeletons alike.
I'm also not totally opposed to a rare chance of stumbling among a stronghold chest on an island as their risk factor is higher of anything else in the game despite their high payout.