This is your most difficult crossing. US border patrol has 2 main concerns about Canadians overwintering in the USA. First, do you have enough money to pay for your trip? Canadians are not entitled to work in the USA without proper advance arrangements as this would be taking a job away from an American. Know your bank account balances and ongoing income from Canadian sources and be prepared to provide proof at the border upon request, such as by logging in to your online banking on your smart phone.
Second, what reasons do you have to return to Canada? US border patrol suspects that Canadians living and traveling full time in their RVs might disappear inside the USA never to return. Since that is not the case, use words like retired, vacation, sabbatical, special trip and/or snowbird to describe the nature and purpose of your trip. When they ask how long your trip will be, always give them a specific return date (eg. the date your travel health insurance expires). In answering their questions, emphasize your ties to Canada, especially business and property ties if any, and your reasons to return, such as to visit family, see your doctor, or resume Canadian employment or business activities.
Finally, don’t try to bring any raw meat, eggs or fruit or veggies grown outside Canada into the USA. Whittle your food stocks down and hit Trader Joes after you are stateside.
In 12 years of going south to the United States snowbirding I have always had to pay duty on purchases over $800 Canadian.