I guess ideally it would be nice to set it per document, similar to VIM's file header functionality, if your familiar...
;
; vi:ts=4:sw=4:noexpandtab
;
I'm thinking since you've got the ignore YAML header stuff, could use it instead to allow per-document options?
The above sets tabspace (ts) to 4, space width (sw)? to 4 and sets noexpandtab for that document only (in VIM)