Getting Visual Studio to deploy a UDF to Return NVARCHAR(MAX)

Question

I have a SQLCLR stored procedure with the following signature in Visual Studio 2013:

[SqlFunction(DataAccess = DataAccessKind.Read, SystemDataAccess = SystemDataAccessKind.Read)]
public static SqlString ExecSql2Json(SqlString sql)

Or alternatively I've tried:

[SqlFunction(DataAccess = DataAccessKind.Read, SystemDataAccess = SystemDataAccessKind.Read)]
public static SqlChar ExecSql2Json(SqlChar sql)

Either way the parameter and return type gets defined as NVARCHAR(4000). I'd like them to be NVARCHAR(MAX).

I know I can manually write my own CREATE PROCEDURE statement to have fine grain control. Is there any option anywhere to change the deploy DDL generated by SQL Server or do I just have to manually add a script to drop and read the UDF with the proper signature?