If it was Cannan, then he would definitely have tried to avoid being part of any door to door enquiries.
But if he was smart enough to avoid the door to doors, and to move a hot car away from his hideout, then why was he so careless with everything a year later, with Shirley Banks and her car etc?
My theory is that Cannan deteriorated mentally and his alcoholism got worse between 1986 and 87. He went from fairly organised in 86 with Suzy, to a much less careful offender with his later murders.
JMO though. I can see why some might argue that Cannan couldn't get away with such a perfect crime, based on his other known offences.