I pretty much want to attach some angle iron to the studs and some threaded rods to the angle iron. I'll rout out the profile of the angle iron into the butcher block so it sits flush and so that when I tighten down on the rods, it's clamping to something solid. I want to drill holes through the butcher block and tighten them down to the edge of the table.
Here's a drawing:
How much max weight do you guys think the edge will support? Will it sag if I was to put my elbows on the table? Could I rest down a 50 pound book bag on the rounded corner, or would that break? How about if a kid was to sit on it? Or even a full size adult?
I know it's not as strong as it would be if I was to simply put a brace there, but with the limited space this is fitting in, I want to be able to use that corner as a third seat. Plus, it'd be cool. Nobody else would have ever seen a floating table that big!
My other option is to use 1/2" hanger bolts and tighten right up to the drywall.