I live north of Spokane...
... Unless you have extreme changes in elevation on the farm, you may not need a repeater. If you mount antennas on vehicles and tractors, and put an elevated antenna at the house, you should be good to go.
In the Palouse?
If all communications are between the house and someone out in the field simplex communications might work well as you describe. However, if they envision communications between people out in the field, the story might be different. As Kaiser cement trucks used to advertise "Find a need and fill it!"