My dwarf SD male is in a 48" x 30" x 18" enclosure and he still stuffs himself under a hide (restaurant bus tub with an access hole) when in shed. A male yellow IMO would at minimum need a 72" x 30" x 18". Personally I'd rather go longer than deeper for enclosures, as reaching into the back of a 30" enclosure to clean it is a stretch already.