How to change gamplay to gamepad on Blacklist Wii U

There's a much easier way. If you want the UI elements off of the gamepad AND the TV, such as the map for example, there are options in the menu to hide them. Just hit minus, then go to options, and there should be an option to hide the map and other UI elements completely. That way they wont clutter up the screen or the gamepad! Happy hunting!

As for displaying on both, I dont think it's possible...

You have significant wireless interference.

The Wii Remotes use a Bluetooth wireless connection, which is a 2.4 GHz frequency. The problem is that many other devices use this same frequency including wireless phones and wifi.

The Wii U GamePad uses wifi technology in its own way, and you could test its effect on the controllers by entering Wii Mode as TV Only, leaving the GamePad off.

Other things to try would involve unplugging wireless phones, keeping cellphones away from you, making sure no one is downloading or watching something via wifi.

Short of playing within a faraday cage, you will never be free of competing wireless signals. The Wii U can handle some noise, but it can be difficult to manage if neighbours' signals are out of your control.