Absolute minimum engine settings for UMG only app.

I’m looking to use an iPad/Android tablet as a control interface for my main project - similar to Unreal’s car demo they did a few months ago. Ideally I’d like the tablet app to be running very minimally on those devices, in order to conserve battery life and run very responsively.

I suppose what I really want is a ‘disable 3d renderer’ configuration in order to use ONLY umg elements.

Any pointers here?