I came across the word in a film which I saw many years ago (not the film mentioned in the OP). My memories of said film are now very hazy: I believe it was fiction (aimed at kids, I have the impression). It involved the doings of lumbermen somewhere in the sort-of-Rocky-Mountains-looking area – or, re the OP, could have been Alaska; they had a frolicsome dog (a Jack Russell, ISTR) called Chainsaw. Generally, wholesome and jolly fun was the scene. I’d been aware, since learning the fact from that film, that the North American tree-felling industry made use of a – substantial in size – piece of kit called a “wanigan”: such an item, featured in the film; and the word was used to refer to it – but I had until reading this thread, completely forgotten what the thing actually was.