Have you tried any creatures with the Unearth ability?Dregscape Zombie and Shambling Remains don't seem to bad.

Actually I changed up the sideboard a bit (I'll update that tonight) to have three Sedraxis Specter . I did look at the other two you mentioned, they seem good. But I feel like they'd hinder more than hurt me.

Lightning Axe is a beast for dredgevine

needs more dredge.

I would recommend some main deck removal such as Fatal Push

Maybe add Hogaak?

Or are you anticipating a ban :)

Stitcher's Supplier is probably the most efficient graveyard filler in the game rn, and is played as a staple in almost all graveyard decks.

Also, if you have been out of magic for a while, maybe you haven't heard of Hogaak, Arisen Necropolis , which you can usually cast by turn three in most yard decks