I GOT IT! The principle is pretty simple but I'm gonna be really systematic with this to make sure I don't screw up.
*denotes double-played card
First turn
Hand: *Walled Village, *Scheme, *Graverobber, Watchtower, +buy card
Action phase: *Walled Village (drawing treasure), *Scheme (drawing treasure), *Graverobber (gaining some kind of cantrip from the trash and topdecking it with Watchtower), +buy card.
Buy phase: At least $6 and 2 buys, buy Watchtower topdecking it with Watchtower, buy Bonfire trashing *Scheme and +buy card.
Cleanup phase: Topdeck *Walled Village, *Graverobber.
Second turn: *Walled Village, *Graverobber, Watchtower, cantrip, something
Action phase: *Walled Village (drawing anything), *Graverobbber (gaining *Scheme from the trash and topdecking it with Watchtower), play cantrip (drawing *Scheme), play *Scheme...
And the rest is noise.
So yeah, something involving Bonfire, Scheme, Graverobber, and Watchtower.
Edit: Okay so this can still work without playing the +buy card (in order to only play 2 things after WV) but you'd need more shuffle luck.