You're on the right track. I don't blame you a bit. I did the same thing a couple years ago.
Disengaging the clutch wants to push the slave cylinder and cover out. If you've ever seen a case that has failed you'll see it is in a natural crevace notch. Also you'll notice the excessive span between two of the bolts holding the case on.
I actually welded up mine and welded in or built up a web of reinforcement of material in that corner notch area. It did fine just doing that. It never did fail again but just in case I have since built my own support for it basically going from a couple solid independant case bolts and strapping across the slave cylinder. I've probably got about an hours time in it and a couple bucks for some longer bolts.