I have been deleting the default code behind file and linking to classes within in my libraries with the following;

<%@ Assembly name="<AssemblyName>" %>
<%@ Import Namespace="<DefaultNamespace>" %>
<%@ Page Language="C#" AutoEventWireup="false" Inherits="<Namespace(s)>.<ActingCodeBehind>" %>

NB: There is no intellisense this way. Furthermore, I am no longer sure if the first two lines are still relevant. Cheers