Welcome to the forum Fidel!
In the eyes of the law, when you remove the tires, and put the AS on blocks, it will not longer be a "motor vehicle," but will instead become an "accessory structure" to your house, and thus subject to your local zoning and building codes.
In other words, you will be opening up a can of worms.
There are threads here which discuss zoning issues, For instance here:
You could also run your ideas by your attorney and other experts incl. builders and architects. If you are within the City of Portland proper, this project will be difficult to do under the radar, unless the site is very private and remote. Way out in the country you might have an easier time.