The only problem again is that I really wasn't interested in making it taste less sweet as much as just having much less sugar. I know you can add things like lemon juice and salt to make it taste less sweet, but it's still a huge amount of sugar.
I still think that there is a way to do it by making a cooked icing sort of RI blend almost. I haven't given up hope!
Try this... make up a batch of poured fondant AKA petit four icing.
It won't dry as firm as RI but that is easily fixed by dropping a square of almond bark in and letting it melt then slowly stir to combine (if you create bubbles they are almost impossible to smooth out).