After finding this solution to enable members to upload images in v8 using the fileUpload dataType, I soon realized the images were being save but only with the file path and not the crops for that field.

After beating my head against the wall for a couple of days I came up with the solution below and it works for me. So if anyone else runs into the same problem this is one way to do it but I want to know if anyone has an easier solution (i.e. fewer lines using the API) to save the uploaded file and the crops.

    static string _imageCropperEditorAlias = "Umbraco.ImageCropper";
    /// <summary>
    /// Saves a HttpPostedFileBase to the file sytem and returns an imageCropperValue for the given ImageCropper dataType
    /// </summary>
    public static ImageCropperValue GetImageCropperValue(this IMember member, string propertyAlias, IDataType imageCropperDataType, HttpPostedFileBase postedFile, IContentTypeBaseServiceProvider contentTypeBaseServiceProvider, decimal leftFocalPoint = ImageCropper.DefaultLeftFocalPoint, decimal topFocalPoint = ImageCropper.DefaultTopFocalPoint)
    {
        if (string.IsNullOrWhiteSpace(propertyAlias))
            throw new ArgumentNullException(nameof(propertyAlias));

        if (imageCropperDataType == null)
            throw new ArgumentNullException(nameof(imageCropperDataType));
        else if (imageCropperDataType.EditorAlias != _imageCropperEditorAlias)
            throw new ArgumentException($"Invalid Datatype: {nameof(imageCropperDataType)} must be of type {_imageCropperEditorAlias}.");

        if (postedFile == null)
            throw new ArgumentNullException(nameof(postedFile));

        if (contentTypeBaseServiceProvider == null)
            throw new ArgumentNullException(nameof(contentTypeBaseServiceProvider));

        ImageCropperValue icv = null;

        // save the file to disk
        member.SetValue(contentTypeBaseServiceProvider, propertyAlias, postedFile.FileName, postedFile.InputStream);

        string src;
        if (!string.IsNullOrWhiteSpace(src = member.GetValue(propertyAlias)?.ToString()))
        {
            ImageCropperConfiguration config = (ImageCropperConfiguration)imageCropperDataType.Configuration;
            List<ImageCropperValue.ImageCropperCrop> imageCropperCrops = new List<ImageCropperValue.ImageCropperCrop>();

            foreach (var crop in config.Crops)
                imageCropperCrops.Add(new ImageCropperValue.ImageCropperCrop() { Alias = crop.Alias, Height = crop.Height, Width = crop.Width });

            icv = new ImageCropperValue()
            {
                Src = src,
                Crops = imageCropperCrops,
                FocalPoint = new 
                FocalPoint = new ImageCropperValue.ImageCropperFocalPoint() { Left = leftFocalPoint, Top = topFocalPoint }
            };
        }
        return icv;
    }

And I call the method like this from my controller...

        if (formData.HeadshotFile != null) {
            var headshotImageCrop = _dataTypeService.GetByEditorAlias(ImageCropperPropertyEditorAlias).Where(c => c.Id == MemberHeadshotImageCropperId).FirstOrDefault();
            ImageCropperValue icv = mbr.GetImageCropperValue(nameof(formData.Headshot), headshotImageCrop, formData.HeadshotFile, _contentTypeBaseServiceProvider);
            mbr.SetValue(nameof(formData.Headshot), icv);
        }