I have not attempted a stout, but my first impression is you need more ferementables. My experience with GF pale ale and GF amber ale is that you have to get up in the OG=1.060 range for the beer to not be thin. By my calcs you are in the OG=1.048 range which I would expect is way too low for a stout. I don't think the steeped oats adds much at all to fermentables.
One example I would use as comparison is:
At first glance, your hop additions are low. If your Fuggles are about 5% AA then you are using 5 AAU on a 7 gallon batch and Igliashon is using about 8 AAU on a 3 gallon batch. By this comparison you would need 2 to 3 times the amount of Fuggles hops you are planning now.
What is the "10 oz of malt"? Is that what you are calling the spices and raisins you are adding to the small carboys?
For gluten free beer we combat three main things, sorghum twang, thin mouth feel, no head retention. Many of us end up using some combination of candy syrup, maltodextrin, higher gravity, and hops to help with those. My advice (if you are going to drink the beer and not just cook with it) would be to consider using more fermentables (get up at least in the 1.060 range), more hops and add some maltodextrin (~1.6 oz/gallon).
Let us know what you end up with and how it turns out!