Unfortunately, that's not possible right now.
In your case, you're using a more powerful mount command, which is not a part of the base.
The only idea I can think of is to add more checker to the core script.
If the util-linux mount exist, use UTF-8, else use busybox.
However, I'm not sure if it will cause any trouble to those non-utf8 partition...
我覺得恐怕很難,需求太小,再加上這會需要util-linux mount,而這並不屬於系統base的一部份
我只能想到去魔改它,用一堆條件確認系統狀態,來決定是否選用UTF-8
比較在意的是這樣一來會不會打亂其他種類的磁碟分割區...