可以通过自定义转换器解决这个问题。首先创建一个自定义转换器类和一个静态中介类，用于实例化和获取转换器。在转换器类中，使用静态中介类中的方法来获取转换器实例，然后使用该实例进行映射。这样，转换器实例将被重复使用，避免了不必要的重复实例化。

下面是一个示例代码，使用自定义转换器来映射列表。

using AutoMapper;
using System.Collections.Generic;

public class MySource
{
    public string Value { get; set; }
}

public class MyDestination
{
    public string Value { get; set; }
}

public class MyConverter : ITypeConverter
{
    private static readonly MyConverter _instance = new MyConverter();

    public static MyConverter Instance => _instance;

    public MyDestination Convert(MySource source, MyDestination destination, ResolutionContext context)
    {
        destination = destination ?? new MyDestination();
        destination.Value = source.Value + " - transformed";
        return destination;
    }
}

public static class CustomMapper
{
    public static TDestination Map(TSource source, TDestination destination)
    {
        return Mapper.Map(source, destination, typeof(TSource), typeof(TDestination));
    }

    public static void Initialize()
    {
        Mapper.Initialize(cfg =>
        {
            cfg.CreateMap().ConvertUsing(MyConverter.Instance);
        });

        Mapper.AssertConfigurationIsValid();
    }
}

public class Program
{
    public static void Main()
    {
        CustomMapper.Initialize();

        var sourceList = new List { new MySource { Value = "A" }, new MySource { Value = "B" } };

        // Use custom method to map a list
        var destinationList = CustomMapper.Map, List>(sourceList, new List());

        foreach (var destination in destinationList)
        {
            Console.WriteLine(destination.Value); // Output: A - transformed, B - transformed
        }
    }
}