What pattern can I use to thin out my RootView?

I've got a RootView in my app that contains a left and a right NavigationDrawer, and inside the NavigationDrawers are a few MvxListView's.

I'm using an MvxFragmentActivity for the RootView

[Activity(ScreenOrientation = ScreenOrientation.Portrait)]
internal class RootView : FragmentActivityBase
{ 
    // huge amounts of code
    //... 
}

internal class FragmentActivityBase : MvxFragmentActivity
{ ... }

The problem I'm having is that my RootView is > 500 lines long, there is a ton of logic in there. What is the Android way to manage all of this logic, and split it out into manageable chunks?

This Gist contains the code in it's entirety
https://gist.github.com/ChaseFlorell/fca61e6b0f40b1acac8f