As soon as the body count starts to rise I see the great experiment coming to an end in a hurry.
If that isn't until the 1930s I imagine that there would be a period where hippo stew and the like is a staple of school meals, soup kitchens and various institutions, at least in the southern states. May as well kill two birds with one stone after all.
You can get Hippo leather in Southern Africa. It’s very strong (like elephant leather) and good for belts.
A quick bit of googling produced a picture of a hippo leather ammo belt, with is of interest given that there's two world wars after 1910. There were also examples of hippo leather boots.