Canadian would like to buy Texan car, drive to Cancun to live for winter, drive return to Canada. Possible?

Yes it can be done. But why? Do you really need a car in Cancun? I would suggest buying the insurance online from a US or Canadian Insurance Co. They can give you coverage that will stay in effect for Mexico also. The premium will be very high if you want vehicles coverage, It may be best to only buy liability coverage and risk the vehicle damage yourself, Traveling in Mexico can be hazardous. I would carry pport, license and not to much cash. Also driving time in Mexico is much longer than you expect.