Catrike expedition looks pretty good, depending on your budget, made in your area as well. I would look at every Craigs list bicycle sale in Florida for possibilities
first. Seems like there would be a large secondary market down there. It would behoove looking at relatively new trikes because of the
revolution in ultralow gearing the past few years. Also depends on how loaded you will be and daily tour mileage. Getting 10mph out of
a trike (on average) will be a bit difficult when one looks at transcontinental touring. That is making assumptions perhaps but not very
many of us at age 70 output more than 2-2.5 watts per kg.