Harvest hosts is a wonderful concept and great for those that enjoy being more rustic. One thing to bear in mind though is that most are just for an overnight (occasionally they'll let you stay a couple of nights!), so unless the specific host is close to the route you are travelling to your ongoing destinations, it could work out rather expensive in time and fuel to deviate too far off. Just saying, as it's a comment others have made.
Another one that's worked out well for those that prefer to dry camp and particularly in areas where city ordinances don't allow one to ON in mall carparks, or in high demand/expensive locations, is Boondockers welcome. To that end anyone coming to Calgary area, we are 11 mins south on an acreage and we have plenty of room, no purchases necessary :)