Regarding this part of your question: "can I convince my future lender (I don't know who he/she is now) that the 2nd property is my main residence (home)?"
The key is, do you plan to actually move into this house within 60 days or so? If the lender has any doubts, they will order an Occupancy Certification which means between 60 - 90 days, someone will go to the property to physically verify that you are in fact living in the house. They will even ask neighbors.
In most cases, if you are "buying up", they will not question it.
I am in the mortgage business and I have an extensive underwriting and loan origination background. I have addressed this issue with lenders many times.