Using an F# ViewModel as designinstance in blend

Question

I have some viewmodels that I've created in F# and would like to use them for designtime data within Blend but I can't figure out how to get this to work.

I have a simple xaml file with some bindings setup as follows:

<UserControl
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:RacePacesUI"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    x:Class="RacePacesUI.RacePaceEntryControl"
    mc:Ignorable="d"
    d:DesignHeight="300"
    d:DesignWidth="400"
    xmlns:SampleData="using:RacePacesUI.SampleData"
    d:DataContext="{d:DesignInstance Type=SampleData:EntrySampleVm, d:IsDesignTimeCreatable=True}">

Where EntrySampleVm is defined as follows:

  public class EntrySampleVm : ViewModels.EntryVm
  {
    public EntrySampleVm()
    {
      Distance = 26.2;
      Time = new TimeSpan(3, 30, 25);
      Pace = 4.0;
      Speed = 16.5;
    }
  }

ViewModels.EntryVm is my F# ViewModel class.

Unfortunately I get an error in the designer:

EntrySampleVm does not exist in this namespace

I have a similar looking C# class defined in the same namespace as follows:

  public class Test 
  {
    public Test()
    {
      Distance = 26.2;
      Time = new TimeSpan(3, 30, 25);
      Pace = 4.0;
      Speed = 16.5;
    }

    public TimeSpan Time { get; set; }
    public double Distance { get; set; }
    public double Pace { get; set; }
    public double Speed { get; set; }
  }

If I then set the DataContext as follows:

d:DataContext="{d:DesignInstance Type=SampleData:Test, d:IsDesignTimeCreatable=True}">

Then it all works as expected so it's definitely the case of using the F# ViewModel.

Is there a way of getting this to work? I don't really like the ServiceLocator approach and because I'm creating a Windows Phone project I don't have access to the x:Static and x:Type extensions.

I'm using Blend Version: 12.0.51020.0 Update 4 VS2013: 12.0.31101.00 Update 4

Thanks for any help