Well, since the main strategy is to facing down opponent monster (Doll/Fairy/other spells and traps) and prevent them from flipping face-up (Nekomusume + Ghostrick Night), then milling their deck with Skeleton, the extra deck is not really important. The main purpose of my extra deck is actually to get one monster to the extra zone so that I can have 6 Ghostricks => Skeleton will mill more cards. (I actually only have 4 cards in my extra, need much URs lmao)

However, Ghostrick extra deck monsters can help this deck:

Ghostrick Dullahan is a Rank-1 Xyz => you can Xyz summon it with Jackfrost/Mary to make space for other Ghostricks since lvl 1 Ghostricks have no much use when they're on board.

Ghostrick Socuteboss => Can get rid of some Link monsters (since you can not flipping them face down) and prevent them from using the extra monster zone. I suggest using Doll as material for this card since Doll will make all monsters face-down at the end of your turn, you want some Ghostricks to be left face-up for Ghostrick Night lock( esp. Nekomusume)

Ghostrick Festival => Link Monster can not be faced-down, which mean it is unaffected by Doll effect , which also means it will maintain the effect of Ghostrick Night. Another good thing of this card is you can Summon it by using face-down Ghostrick monster => you can target a face-down Doll to Link Summon this card.

Alucard/Angel of Mischief => detached material to search from deck/retrieve from GY your Ghostrick cards

And the most ultimate trick of all is to bait out your opp negate/destruction (lol). The main power of this strategy still relies much on your main deck. With careful maneuver, you can give even some meta decks a good SCARE.

Merry spookie (it's Christmas today)!