This is a simplified edition of yours (with a lot of stuff hard coded for proof of concept):

public static void MyLoadProperty2(this ObjectContext objectContext, TEntity entity, string navigationProperty) where TEntity : class
{
ObjectQuery query = objectContext.ObjectStateManager.GetRelationshipManager(entity).GetRelatedEnd(“FK_Customer_has_Orders”, navigationProperty).CreateSourceQuery() as ObjectQuery;

Type related = query.GetType().GetGenericArguments()[0];

typeof(ObjectContextExtensions)
.GetMethod(“LoadRelatedHelper2″, System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static)
.MakeGenericMethod(related)
.Invoke(null, new object[] { query, MergeOption.NoTracking });
}

private static void LoadRelatedHelper2(ObjectQuery query, MergeOption mergeOption)
where TRelated : class
{
query.Context.CreateQuery(“select value v from orders as v where v.Customer_RecordID = @Customer_RecordID”, new ObjectParameter(“Customer_RecordID”, new Guid(“FAD85849-6631-4B71-A311-58C1DF3E515F”))).Execute(mergeOption).ToArray();
}