DS HATED applesauce so we used either baby bananas or pears. In a pinch I've used grape jelly, ketchup and chocolate syrup. I've seen what enzymes do in milk/dairy -- they break down fairly easily, so even without the fat, I'd be hesitant to use even skim milk.
All you need is a tiny amount of fruit, don't need a whole bowl or a ton of liquid, just a teeny amount to get them to stick to the spoon to get them in the mouth.
On a side note, do you think he's old enough to take pills instead? Might be easier..