This may be late, but I was jsut looking through some post.
My now 2 year old was on Rice milk from 12mos. to 18 mos. We saw a dietician at the Feeding Clinic and she recommended the following:
Enriched Rice Milk - Vanilla flavor has a few more calories
Cocunut Milk for the fat (read the label, I think like 2 tablespoons is like 8 grams of fat)
1 tablespoon or MLO Rice Protein
and I also added Strawberry Nesquick for the flavor.
He loved it and he got his fat, protein and calcium.