I recently went thru the same max length exercise, cuz I wanted a longer USB cable RATHER THAN a bigger whole to cut (to get thru the big plug of an extension cord).
I beLIEve the total max length is 16.4 feet, UNLESS you get an “Active” USB cable. This product from Amazon… https://www.amazon.com/gp/product/B00KY9M51O/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1 gave me the 21 or so total feet I needed. The camera works great.