Thank you, All!
Yes, pulling the mane and clipping the head/legs definitely should be done in advance. Although I can't really clip ears on one of my mare (yes, yes, tried everything for months, still barely handles scissors
I was thinking about putting her in stall for the night, but my biggest concern stupid animal poops and pees ALL over the stall, mix it up evently, and then sleep on top of it fully stretched (unlike my other mare that is very clean in her compartment).
So I wonder how to clean up those poopy spots on neck and head on day of show...