If anyone in the future is interested, my solution was to make the colors more faint (used W3 School's html color picker to get what I wanted) like so:

/*Modifications for evaluation tables (Unsatisfactory - Far Exceeds)*/
.cf-table th {display:none;}
.EvalTableEmp span.choice {text-align:center;}
.EvalTableEmp span .form-option-label {color:black}
.EvalTableMan span.choice {text-align:center;}
.EvalTableMan span .form-option-label {color:black}
.FarExceeds {border-radius: 5px; background-color:#cce0ff;}
.ExceedsReq {border-radius: 5px; background-color:#d6f5d6;}
.MeetsReq {border-radius: 5px; background-color:#f2f2f2;}
.NeedsImprovement {border-radius: 5px; background-color:#ffe0cc;}
.Unsatisfying {border-radius: 5px; background-color:#ffcccc;}

Then I run the resulting entry through this black-and-white conversion script:

namespace WorkflowActivity.Scripting.RemoveColor
{
    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Data.SqlClient;
    using System.Text;
    using System.IO;
    using System.Windows.Media.Imaging;
    using System.Linq;
    using Laserfiche.RepositoryAccess;
    using Laserfiche.Imaging;
    using Laserfiche.DocumentServices;

    /// <summary>
    /// Provides one or more methods that can be run when the workflow scripting activity is performed.
    /// </summary>
    public class Script1 : RAScriptClass104
    {
        // this value seems to match the results we get from the Quick Fields Remove Color process.
        //const int BITONAL_THRESHOLD = 130;
        const int BITONAL_THRESHOLD = 170;
        /// <summary>
        /// This method is run when the activity is performed.
        /// </summary>
        protected override void Execute()
        {
            if(BoundEntryInfo.EntryType != EntryType.Document)
            {
                WorkflowApi.TrackError("The specified entry is not a document");
                WorkflowApi.TerminateWorkflow("The specified entry is not a document");
            };

            DocumentInfo doc = (DocumentInfo)BoundEntryInfo;

            if(doc.PageCount == 0)
            {
                WorkflowApi.TrackError("The specified document has no pages");
                WorkflowApi.TerminateWorkflow("The specified document has no pages");
            }

            if(doc.GetPageInfos().All(d => d.ImageDepth == 1))
            {
                WorkflowApi.TrackWarning("The specified document is already black and white");
                WorkflowApi.CompleteWorkflow("The specified document is already black and white");
            }

            DocumentExporter exporter = new DocumentExporter();
            exporter.PageFormat = DocumentPageFormat.Tiff;
            MemoryStream stream = new MemoryStream();
            PageSet pages = new PageSet(new PageRange(1, doc.PageCount));
            exporter.ExportPages(doc, pages, stream);

			LfiBitmapDecoder decoder = new LfiBitmapDecoder(stream, BitmapCreateOptions.None);
			LfiBitmapEncoder encoder = new LfiBitmapEncoder(LfiContainerFormat.Tiff);

			// We need to do some gyrations because SSRS outputs multi-page TIFFs that also have RGB sub-pixel rendering.
			foreach (LfiBitmapFrame frame in decoder.Frames.ToList())
			{
				LfiBitmapSource source = new LfiWriteableBitmap(frame.DecodeBitmap());
				LfiGrayscaleThresholdBitmap bw = new LfiGrayscaleThresholdBitmap(source, BITONAL_THRESHOLD);
				LfiBitmapFrame newFrame = new LfiBitmapFrame(bw, LfiBitmapCodec.FaxGroup4);
				encoder.Frames.Add(newFrame);
			}

			MemoryStream ms = new MemoryStream();
			encoder.Save(ms);

            doc.DeletePages(pages, PageDeletionOptions.ForcePurge);

            DocumentImporter importer = new DocumentImporter();
            importer.Document = doc;
            importer.ImportImages(ms);

			ms.Dispose();

			doc.Save();
			doc.Unlock();
			doc.Dispose();
        }
    }
}