In a medium bowl, stir yeast into warm water; set aside. In the bowl of a stand mixer, combine cake mix, salt and 4 cups of the flour. Stir in the yeast and water. Gradually add the last cup of flour until the dough pulls away from the sides of the bowl and a soft but slightly sticky dough forms.

Cover with plastic wrap and let rise in a warm place until dough is doubled in size, about 60 minutes.

Turn dough onto a large, floured surface and knead once or twice. Roll dough into a rectangle about 12 inches wide, 28 inches long and 1/4 inch thick.

Spread soft butter evenly over dough. Combine sugars and lemon zest and sprinkle over butter.

Once you have spread the butter and sugar mixture over the dough, cut the large rectangle in half to form two smaller rectangles. Starting with a long end, roll each rectangle into a log. Slice the dough into 1 to 1 1/2 inch pieces.

Place the rolls into 2 greased 9x13 pans (or a 9x13 and a 9x9, depending on how many rolls you have). Cover the rolls and let rise until doubled in size, about 40 minutes.

Meanwhile, preheat oven to 350 degrees. Bake rolls for about 20-25 minutes, or until golden brown.

While rolls cook, beat the cream cheese and butter for the frosting with an electric mixer until creamy. Mix in the vanilla and 1 tablespoon of lemon juice.

Gradually add the powdered sugar and salt, mixing until smooth. Add more lemon juice, if needed, until frosting reaches desired consistency. Spread frosting over hot rolls.