I finished up the dome today, I'll add pictures as soon as I scoop the sand out, which might be a night this week or next weekend, rain started coming down as I was putting the tarp on, though it looks like the rain is mostly holding off until later tonight. I added refractory needles in this mix to help with the structure of the dome once the sands removed. I'm hoping for the best when I dig out the sand, and I do have enough cement left for a second dome if needed.
It is a bit small but I think I should be able to get a 12" pie on there with a fire, though the pies may end up having to be even smaller than that. I don't really foresee the fire being larger than 10" wide. I imagine I'll have to have a long heat time, and then a smaller fire once I've pre-heated.
If you watch starting at 2:18, it looks like he has a flame in the back.
The stand is holding up fine, the legs are pretty well designed to attach to the grill base without wobble, but the plastic wheels have been compressing more and more as I add weight to the top, so I'll definitely have to reinforce those, or at least prop them up, since those legs are about an inch shorter than the stationary legs.