Is this project still active?
HDplex are making a 300w internal psu. Would it fit?
I'm looking at the dimensions and it should fit if you don't use any 2.5" drives. If you have the DC-ATX mounted under the motherboard and you turn the brick on its side and mount it against the GPU side panel, then you're looking at 51.5mm width for the DC-ATX + 41mm width for the upcoming 300W AC-DC brick = 92.5mm. Plus 4mm of wall and 2mm of double sided tape/velcro for the brick = 98.5mm. And the case is 99.9mm wide so it should barely fit. It would add heat to the GPU compartment. And, again, no 2.5" drives. But you do get a passive internal 300W PSU.
That is, if Hahutzy is still on this project.
PS On second thought, the brick may hit the riser mounting bracket on the GPU side. GPU width clearance seems to be about 39-40mm and the bracket is probably 1-2 mm. And the brick is 41mm on its side. Seems like it won't work, tho we'll really need exact numbers here. If it fits, it will take force or a mod and be incredibly tight.