Base: Cut margarine into flour in a bowl until mixture crumbles.
Press crumb mixture into anungreased 7x 11 in.(17x27 cm)baking pan.
Bake at 350°F (175°C) for 12 to 15 minutes, or until lightly browned.
Filling: Beat eggs in a bowl until light and lemon-colored.
Gradually beat in fructose, sugar replacement, and vanilla extract.
Stir in coconut and baking powder.
Spread mixture over baked base.
Return to oven, and continue baking for 20 minutes more, or until surface is lightly tanned.
Cool on rack.
Icing: Combine fructose, sugar replacement, cornstarch, and aspartame sweetener in a small food-blender container.
Blend, turning the blender from High to off for about 10 seconds.
Pour mixture into a small mixing bowl.
Add lemon rind.
Stir in just enough lemon juice to make mixture smooth and of a thick liquid consistency.