Yes, without any "No Trespassing" signs posted, it appears country girl has little legal recourse. Here is a link to Minnesota's trespass law, 609.605:
https://www.revisor.mn.gov/statutes/?id=609.605
Even
with signs up, though, a photographer could still take photographs of country girl's property and barn from the public road, and publish these photographs. The photographer would just have to take care not to trespass onto the property to take a shot.
Minnesota also has an invasion of privacy criminal statute, 609.746, but it does not apply to what has been provided in the way of facts here:
https://www.revisor.mn.gov/statutes/?id=609.746
Minnesota has recognized since 1998 three of the four invasion of privacy torts: publicity given to private facts, and intrusion into one's seclusion, and misappropriation of one's name or likeness (the other privacy tort - false light - falls under Minnesota's defamation law). The elements of each of these torts mimic the ones outlined in the Pennsylvania
Boring v. Google case.
The elements necessary to support an invasion of privacy civil action do not seem to be present with what country girl describes as her situation with the calendar and tour.
country girl's best course of action may be to appeal to the better nature of the photographer/tour guide and request her property address be removed from the tour (although I am still partial to Stephan's suggestion).