I think I have a reasonable way to clean up green creature combo decks a bit now that I'm so committed to not caring about duplicates. In particular, you have a couple of cards that exist entirely in their own "green deck" space: Glimpse and Earthcraft. Now, both glimpse and earthcraft rock and perfectly reflect my goals except with a small creature flavor. So I want to keep these four slots (maybe 6 slots with Cradle and Visionary) the same. But how do I make sure these greens decks are well supported with a cast of other cards to play? This way we have the small core of "creature combo" and then the rest can be whatever.

The key is that Glimpse and Earthcraft absolutely do not care what kind of creatures you play as long as they cost 1 or 2. In fact, you don't even need mana dorks really, since Earthcraft and Cradle are fueling your mana generation. So then we can just go the 3x of the premium green 1 drops that many decks want to play: Elvish Reclaimer and Deathrite Shaman. The reclaimers even act as an additional way to get Cradle, making your mana burst more consistent. And Reclaimer and DRS are a strong enough plan B on their own to help with robustness.

So now we have a very clean separation of concerns. We have some good cards. And then we have the dedicated green creature combo slots. Since reclaimer and DRS are both elves, we can try out an Allosaurus Shepherd as a test slot. But all these dedicated slots should work with the rest of the card pool not the other way around.