Well, I got this to work (I lied, I guess there's 3 layers), but it is soooo slooooowww:

<ul>
 @foreach (var page in @Model.AncestorOrSelf().ProductList)
 {
  if (page.Childen != null && page.Children.Count() > 0)
  {
   <ul>
    @foreach (dynamic secondPage in page.Children)
    {
     <li>
      <h3><a href="@secondPage.Url">@secondPage.Name</a></h3>
      @if (secondPage.Childen != null && secondPage.Children.Count() > 0)
      {
       <ul>
        @foreach (dynamic thirdPage in secondPage.Children)
        {
         <li>
          <h4><a href="@thirdPage.Url">@thirdPage.Name</a></h4>
          @if (thirdPage.Childen != null && thirdPage.Children.Count() > 0)
          {
           <ul>
            @foreach (dynamic fourthPage in thirdPage.Children)
            {
             <li>
              <h4><a href="@fourthPage.Url">@fourthPage.Name</a></h4>
              @if (fourthPage.Childen != null && fourthPage.Children.Count() > 0)
              {
               <ul>
                @foreach (dynamic fifthPage in fourthPage.Children)
                {
                 <li>
                  <h4><a href="@fifthPage.Url">@fifthPage.Name</a></h4>
                 </li>
                }
               </ul>
              }
             </li>
            }
           </ul>
          }
         </li>
        }
       </ul>
      }
     </li>
    }
   </ul>
  }
 }
</ul>
 

The content looks like:

Home
-Products
--Group1
---Category1
----Type1
-----Product1
-----Product2
----Type2
-----Product3
-----Product4
---Category2
----Type2
-----Product5
-----Product6
--Group2
---Category3
etc, etc, etc.
-About
-Contact

The included Razor macros like the SiteMap are so fast, compared to what I've done, I'd sure like to find a way to take advantage of them.  I just could not figure out a way to get them to start at Products, instead of Home.

I don't know if it matters that each product has ~25 properties, about a third of which will be images.  Ultimately there will be about 200 of them.  Seems like performance will only get even worse as I poplulate the site with data.

Thanks very much for any help.

Matthew