Starter for a gluten free beer using chestnuts

I'm going to make a starter for a chestnut beer I'm doing for a gluten intolerant friend of mine.

The fermentables I'm using are corn sugar, Belgian Candi sugar, and of course the chestnuts which Wikipedia says this of:

"Their carbohydrate content compares with that of wheat[35] and rice; chestnuts have twice as much starch as the potato.[29] In addition, chestnuts contain about 8 percent of various sugars, mainly sucrose, glucose, fructose, and, in less amount, stachyose, and raffinose."

Now my starter for sure will include the two sugars, but I'm wondering if I should make a mini wort with the chestnuts for the starter so I don't confuse my yeasties when they are pitched. With this sugar makeup for chestnuts would it matter? Or would the taste of Candi sugar and corn sugar put them on track enough to keep on truckin'?

Have you considered using molasses?

Well I was going to use brown sugar until I learned that might leave a molasses flavor. I'm trying to mimic a strong Belgian Ale, and I don't know if molasses would go well with that.

Are you using amylase enzyme to convert the starch?

Yes, I was thinking if I was to make a small wort for the starter I'd use a half handful of roasted chestnut chips and soak them for 12 hours with a pinch or two of amylase enzyme to free them up. I am just wondering if this mini wort is necessary or if the sugars in the corn sugar and candi sugar would be enough to build an enzyme profile for the yeast to use.

Mini wort isn't necessary, but if you are using just sugars for the starter, you should include some yeast nutrient. The yeast need nitrogen for strong growth.

How much nutrient should I add?