Wpf – How to rotate Text in WPF by keeping the Auto-Sizing function

I want to have an text vertical. I just use a simple grid in WPF to auto-size the areas. But when using RotateTransform, all calculations are wrong. Any idea how to solve this?

        <Grid.RowDefinitions>
            <RowDefinition Height="*" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>

In this image you see what I mean. If I now want to auto-size the middle part I cannot use "Width" or "Height" property because both will raise a wrong sizing result. Width =120px will increase the horicontal (original) width and will make the complete row 120pixel. Height=120px will make the text 120pixel height.