To reclaim as your primary residence, your tenants need to become room mates, without exclusive use to the property (or a secondary suite). It seems to me that your largest issue is to change the rental contract.
So, I guess you may need to talk to them, and get them to agree to go into a new contract as room mates voluntarily. Alternatively, you can give them the eviction notice and offer to keep them on as roommates. The fact that your bedroom is actually a sofa in the basement, that you rarely use, may be secondary. They are responsible for collecting and forwarding mail when you are away.
Now, for US residency rules, and taxation, etc., you actually need to be present in the USA (and state) for X number of days per year to be taxed in that jurisdiction as a resident... and I can't see how you claim primary residence for a location that you occupy less than xX? days per year....? Maybe there is a loophole Canada relies more on the fact that you are a resident AND you can only claim one place at a time as primary, so maybe the US is the same.