Excellent essay, Anne. Although your lifestyle is nothing like mind, our work situations have many similarities. In 1997, I quit my regular job and started a bookkeeping service. Later, I would add an employee and then decide I was better off alone.
I have no paid time off. Every sick day, every vacation day is without pay. I was fortunate that my health insurance was covered by a survivor's policy when my previous husband passed. I pay both the employer's and the employee's side of Social Security (national retirement).
But, I control my fees and that more than makes up for the additional expenses I have. I love being independent, especially now during the pandemic. Because employees in my client offices were not wearing masks, I changed my schedule to work when others aren't around. If my clients hadn't agreed, I would have quit. Of course, now I qualify for Social Security but haven't taken any because I am still working. Having that as a security net is very helpful. Still, I greatly enjoy my independence.
Your work is physically taxing; I hope you can continue with it for a long time, but always be thinking about work that isn't so physical for your later years. By then or before, I imagine you will be a fulltime travel writer!