RasPi3B+ with RemotePI and offical screen - how to power?

I am planning this setup:

Raspi + Hifiberry Digi+pro + official Screen + RemotePi.

I figured out how to deal with remotePi and the Hifiberry. But how to power the screen? This should be turned on and off by the remotePi board as well!
I want to avoid an extra power supply for the screen…
Is it possible to power the screen via USB out from the Pi? Without getting the yellow undervolt sign?
Any Ideas?