From my understanding the trappers cabins are intended for a fairly limited use, to reduce the potential for abuse. It is possible to get a recreational lease to allow a cabin/development on public land, although these are more intended for something open to the public year round. In the Grande Prairie area, Dion (sp?) with Sustainable Resource Development 780-538-8080 can provide more details on what is allowed for other use, or what may be determined as unauthorized and can be removed (possibly burned down) after the 14 day maximium stay. They are quite reasonable with this, if you have a wall tent setup for hunting season for example, they realize it might be longer than 14 days. However if it becomes a year-round semi-permanent cabin it would be posted with a warning, then removed and auctioned if no efforts made to claim it by the owner.
http://www.srd.gov.ab.ca/lands/using...ping_Final.pdf
http://www.srd.gov.ab.ca/lands/using...ngprogram.aspx
Hopefully the links work.