The rule for adding suffixes is to add them directly to the word to form a solid word. The suffix –wise normally follows this rule.
…We placed it lengthwise along the edge.
…Otherwise, he will not be able to complete it.
This suffix, however, gets added to some words where it was never intended: punctuationwise, doctorwise. How do these words look? Are they readable? We may have to hyphenate the –wise ending if readability becomes an issue.
When adding any suffix to a multiple-word compound, it is hyphenated to the last element.