I will play as I finish packing for tomorrow....

So you need to know the density of Cream of Coconut which is about 10.16 oz per US cup (I had to look that up). A cup is 8 oz as you know.

Density = mass/volume, therefore volume = mass/density

Volume = 8/10.16 = .8...this confirms your 15 oz weight = 12 fluid ounces

You are measuring the other 2 items by fluid ounces so my vote is to go with 12, 12, 48 fluid for all ingredients

Having said that I usually mix the mixers and then adjust by taste...:)

Your OCD friend....