Resolve ViewModels in WinPhone 8.1, Prism and Unity - xaml

Question

I am developing an Windows Phone 8.1 App with Prism for Windows Store Apps and Unity as IoC container. I got the basics working so far and the convention based resolving of View and ViewModel works so far.
For navigation I want to use a Drawer Layout (with a flyout menu) and display the selected models inside the MainPage (rather than navigating to pages).
So I have a MainViewModel (which gets correctly instantiated and assigned with MainPage, using a custom name convention). And I have a DrawerViewModel. The drawer is inside the MainPage, where also the other ViewModels shall be displayed.
My MainPage.xaml:
<Page
x:Class="StackExchangeReader.Views.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:StackExchangeReader"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:m="using:StackExchangeReader.Models"
xmlns:drawerLayout="using:DrawerLayout"
xmlns:prism="using:Microsoft.Practices.Prism.Mvvm"
xmlns:designViewModels="using:StackExchangeReader.DesignViewModels"
mc:Ignorable="d"
prism:ViewModelLocator.AutoWireViewModel="True"
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"
d:DataContext="{d:DesignInstance designViewModels:DrawerDesignViewModel, IsDesignTimeCreatable=True}">
<Grid x:Name="RootLayout">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<!-- Title Bar -->
<Grid x:Name="TitleBar" Background="#00ADEF" Grid.Row ="0" Height="60">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Image Margin="5" x:Name="DrawerIcon" Grid.Column="0" Source="/Assets/drawer_icon.png" HorizontalAlignment="Left" Tapped="DrawerIcon_Tapped" />
<TextBlock Grid.Column="1" Text="{Binding Title}" Foreground="White" VerticalAlignment="Center" FontSize="18"/>
</Grid>
<!-- Drawer Layout -->
<drawerLayout:DrawerLayout Grid.Row="1" x:Name="DrawerLayout">
<Grid x:Name="MainFragment" Background="White">
<!-- Main Content goes here -->
</Grid>
<Grid x:Name="ListFragment" Background="#F4F4F4">
<ListView DataContext="{Binding Sites}">
<ListView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=Name}" Margin="10" HorizontalAlignment="Left" VerticalAlignment="Center" FontSize="18" Foreground="Black" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</Grid>
</drawerLayout:DrawerLayout>
</Grid>
</Page>
The two things here to be notice are:
MainFragment Grid, where the other ViewModels shall be displayed (i.e. after clicking an option in the Drawer Layout menu)
ListFragment Grid, with the options the user can select
Now the actual problem/question:
Since Prism resolves ViewModels and Views by convention, of course...
... it won't resolve the DrawerViewModel.
I can't instantiate it in XAML, cause it doesn't have a parameterless constructor and it has dependencies injected, so it's required that it's resolved via Unity.
Adding a property in MainViewModel could be possible, but then I'd need to inject it. While it would solve this one problem, it doesn't solve the problem that I also need to instantiate the Content (inside MainFragment) too. Also it's a bad idea to make ViewModels independent of each other. After all, MVVM should support loose coupling.
I also tried to define ViewModel dependency on the MainPage class, but Prism/Unity do not seem to be call this constructor (which Unity should do, if they were to be resolved via IoC/DI, because Unity chooses the constructor with the highest number of dependencies when it resolves the class)
I could also inject the IoC container into the MainViewModel, but this makes my ViewModel(s) depend on IoC. And passing IoC into ViewModel is a bad practice anyways.
I also considered using an abstract factory. This would avoid dependency on IoC container, but it feels like it only shifts the problem.
First things first:
What would be the correct and elegant way to assign an instance of DrawerViewModel as ListFragment's DataContext?
Could designing the ListFragment as an UserControl help allow me that the DrawerViewModel is correctly resolved and assigned to it? Anyone (preferably with Enterprise Business Application experience) having the same issues and a solution for this problem?
Just for the record, the two ViewModel classes.
MainViewModel.cs
public class MainViewModel : ViewModel
{
private INavigationService navigation;
private IEventAggregator events;
public MainViewModel(INavigationService navigation, IEventAggregator events)
{
this.navigation = navigation;
this.events = events;
}
public string Title { get; set; } = "Example";
private ViewModel selectedViewModel;
public ViewModel SelectedViewModel
{
get { return selectedViewModel; }
set { SetProperty(ref selectedViewModel, value); }
}
}
DrawerViewModel.cs
public class DrawerViewModel : ViewModel
{
private ISiteService siteService;
private IEventAggregator events;
public DrawerViewModel(ISiteService siteService, IEventAggregator events)
{
this.siteService = siteService;
this.events = events;
sites = new ObservableCollection<Site>();
}
private ObservableCollection<Site> sites;
public ObservableCollection<Site> Sites
{
get { return sites; }
}
}