I have been told a couple of times, to come back with proper visa.
They always let me in.
The last time (a few weeks ago), they leaned on me, that I should get the proper visa.. This time they seem kinda serious. In the past year or so there are a lot of new and different visa options... I am sure you can find something that will work for your situation.
You can always do what you want. but if the deny you entry at the airport, where you go from there may not be your choice. They could deport you to your home country or they could simply allow you to fly to another country of your choosing.
It used to be less of an issue. I have "abused" the system with reckless abandon, but the last time I came in the immigration officer pulled me aside and read me the riot-act. He made a point that in the past they were more flexible but they now have more visa options so there is no reason to 'work the system'
You may get questioned about it but in the end, they won't care.
If you do get questioned about, keep calm be ultra respective, compliment Thailand, people food, etc. (Some westerns think its a good idea to get an attitude in these situations - it's not a good idea).
A lot can change in 3 years. I can decide to move to Thailand and the next day get a plane and be here, living in Thailand. It's really not much more complicated than that, for the Thai side of things... For the Canada side of things.. I would make sure you have a phone set-up, current driver's license, all your banking needs arranged.
In the US, the state where you reside, determines your tax liability, not sure how its done up north but you want to look into best tax situation.
Yeah - they seem to be cracking down on appropriate visa types. I have been using METV for while now, but my last entry (2 weeks ago) they pulled me a side and told me to get the correct visa. They've done that in the past but this time, there are more visa options so I think they were kinda serious.
I recently got a new passport. My previous passport was full of tourist stamps. When I got my new passport I simply left Thailand. They added two stamps when I exited. One stamp was a reference to my previous passport and the other stamp was my exit stamp.