It sounds like a fun project, so go for it if you want to. Here are a few ideas:
1. What benefit do you think you are going to get out of this compared to a ceramic cooker, other than size? It seems to me that the drums and domes are only there to hold the DE in place, so you could take the next logical step and think about removing them once the "ceramic" is set.
2. I think the hinged lid is going to be a major challenge here, due to its weight and the fact that the DE may or may not be completely fixed after repeated openings and closings of the lid.
3. You will need an efficient way to remove ash. I wasn't clear on how many openings you were planning in the drum(s) for access to food, fire and ash, but as you say, this should all be planned up front.
4. Finally, I would recommend you consider the effects of differential thermal expansion of the steel and the DE, as well as the differential expansion of set, loose and wet DE, as these factors could have some significant impact on the structural integrity of your refractory layer.
If you so this, please post pictures! Good luck.
The Smokin' Badger
Klose Widebody MasterChef * XL BGE * WSM * Weber Performer * La Caja China * Cookshack 055 *
Big Stainless Gasser *