That's the approach Sedeewick of the (in?)famous textbook takes. He also has one neat tweak that simplifies rebalancing: when traversing a B-tree for insertion,

That's the approach Sedeewick of the (in?)famous textbook takes. He also has one neat tweak that simplifies rebalancing: when traversing a B-tree for insertion, preemptively split any full nodes as you visit them. This ensures there will always been room in a parent node if child nodes force keys up.