I have three 20 cm diameter by 7 cm height baking pans. Is the 7 cm height to high to use for a three layer cake? I obviously don't plan to fill than to the top - just to split the quantity of the cake equally into the 3 pans?
So that's almost 8"x almost 3". They should work fine. As you said, divide the batter equally among the three pans. The height of the sides is not important as long as they are high enough to contain the batter.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan