I'm replacing the ancient, decrepit circuit panel in my old RV with a new Square-D HOM612L that has two hot buses:

[![enter image description here](https://i.stack.imgur.com/9dQbG.png)](https://i.stack.imgur.com/9dQbG.png)

The problem is that I only have one hot wire coming in (the standard 30-amp plug found on most all RVs). Every tutorial/example for wiring a 30-amp subpanel that I'm finding starts off with an assumption of four incoming wires—two hot, one neutral and one ground. That's not the case here. I only have three to work with.

I propose to use a heavy jumper wire between the two, but I don't know whether that's safe or allowed.

How do I activate both buses?