I changed Skipper into Locksmith.
Locksmith Action - Duration,
+2 Cards
At the start of your next turn,
+1 Card
You may treat a duration card you have in play as if each of your turns is the next turn.
(For that card, this is the start of your next turn.)
Locksmith unlocks your duration bonuses. Get tomorrow's bonuses today! For example, you can play Wharf and get +2 Cards and +1 Buy. Then you play Locksmith to unlock it's additional 2 Cards and Buy this turn. (You discard it at the end of this turn.) Turn Caravans into Labs. Turn Caravan Guards into Peddlers. Turn your Merchant Ships into +. Sometimes you don't want to fast forward your duration cards. For example, you want the attack bonus that Swamp Hag gives, but that's okay, it's nice to have the option. For cards like Champion and Outpost, this won't give you anything, but that's okay too; it doesn't mess anything up either. Sometimes there are no other duration cards in the supply, that's also okay because you can play it on itself. Usually Locksmith is 2 cards now and 1 later, so that's slightly slower than a Smithy, but if you play a second Locksmith you can unlock the first one to get your full three cards. But maybe you don't want all those cards now? That's fine. You have enough this turn, you can save some of them for the next one.
One problem is that as worded, you can use Locksmith on itself, making it just a strictly better Smithy. I see from your explanation of the card that that's not intended, but that's how it's worded. Also, the wording just isn't really clear and doesn't describe what you intend it to do. Durations give their bonus "at the start of next turn", so if you play a Merchant Ship and then a Locksmith, I don't really see how "each of your turns is the next turn" matters, because it's already past "the start" of the next turn; now it's in the middle of the next turn.
I think a more accurate wording might just be "execute the start of next turn effects of a Duration you have in play". It's not official Dominion language, but it's pretty clear. With this wording and your wording, it's not clear if you intend for it to be able to be used on a Duration you played last turn as well as one you played this turn. The wording seems to imply you can.
There's also issues with cards like Tactician, Haven, Gear, and Archive... If you use it on Tactician, do you get the bonus? Probably not, because you never discarded a card to it. If you use it on Archive, do you just get 1 of the set aside cards immediately? Thus causing Archive to be discarded a turn sooner than normal?
Finally, assuming you make it not work on itself like you want, then in a board without other Durations (which is a lot of boards), it's just a strictly worse Smithy.
I changed Locksmith from "a duration card you have in play" to "another duration card you have in play".
If you use it on Tactician, you get the bonus if you discarded your hand. Otherwise you don't. You usually wouldn't choose (nor have the opportunity) to Locksmith a Tactician.
For Haven, you set aside a card, then Locksmith it to put it into your hand. This turns Haven into simply +1 Card, +1 Action. You usually wouldn't choose to Locksmith this.
For Archive, it says "each of your turns", so now is the next turn, and your next turn is the turn after that. So you play Archive, get one of the three cards, Locksmith it, get one of the two remaining cards, then at the start of your next turn you get the third one. If you Locksmith it again, you get all three cards this turn.
And if it's the only Duration, it's not strictly worse than Smithy because sometimes you actually want to have extra draw for this turn instead of next turn, especially in cases where you overdraw your deck. But you're right that it's
usually (but not strictly) very slightly worse than Smithy. If you play 4 Smithys, you get 12 cards this turn. If you play 4 Locksmiths, you get 11 this turn and 1 next turn. For all future turns that you play 4 Locksmiths, you get 12 cards this turn because you get the extra one at the start of your turn, so yes, that's weaker than Smithy, but you get 1 card fewer the first time you play a chain of Locksmiths and then the normal amount there on out, so that's an extremely minor weakness.