Potatoes added to breads is not unusual as it may seem. Potatoes help breads retain more moisture, makes them lighter and help increases shelf life.
Rye flour has less gluten, proteins found in bread, than wheat. Gluten is what makes bread sticky. Rye tends to produce heavier and denser breads. Potatoes added help lighten rye breads and wet helps compensate for gluten consistency and Proportions are important.
This recipe produces a lighter rye bread and makes terrific toast. It can be made in a loaf pans or free formed. If making them into larger rounds like the picture shown, make sure you add enough wheat to give it sufficient substance.
Even with potatoes, breads without preservatives have relative shorter shelf lives. Once cooled consider storing portion sizes in the freezer.