Facility to run code explicitly implemented in a base class that does not follow CA1033
This is a pretty tidy implementation, not much to say here. A couple very minors:


This is a bit hard to read:


return new ReturnMessage(.Invoke(instance, args), args, args.Length, methodCall.LogicalCallContext, methodCall);



I'd split it up:

var targetMethod = map.TargetMethods[Array.IndexOf(map.InterfaceMethods, (MethodInfo)methodCall.MethodBase)];
return new ReturnMessage(targetMethod.Invoke(instance, args), args, args.Length, methodCall.LogicalCallContext, methodCall);

Clone the argument array instead of explicitly copying it:

var args = (object[])methodCall.Args.Clone();


Expresses the semantics on a more compact way.
For me this seems to be some sort of method forwarding so I'd possibly consider renaming it and maybe turning it into an extension method (I like the syntactic sugar of it). Something along these lines:

public static TInterface ForwardToBase&lt;TBase, TInterface&gt;(this TBase @this)
    where TBase : TInterface
    where TInterface : class
{
    return (TInterface)new ExplicitImplementationProxy(typeof(TBase), @this).GetTransparentProxy();
}


In which case the call would then read as:

this.ForwardToBase&lt;BaseClass, IExampleInterface&gt;().InterfaceMethod()