You just don’t.
Leave the matter be and shove it in the linen closet when he’s done running around underneath it, banging into corners and walls while blinded. Wrinkled and all.
Dad won’t notice when it’s stretched across the bed later on anyway and it makes it easier for Mom to pick up the ten million other things he’s strewn about everywhere while she’s been doing the improbable task of “getting ready”.
Hopefully I’ve solved someone else’s similar issue.