Airport with no ICAO code

This is not strictly SDK related, but I am wanting to create an airport that doesn’t have an ICAO code. It has an ident of AU-0322 but the 2020 SDK doesn’t allow hyphen or any more than 5 chars. I read in this thread that 2024 seems to allow 6 chars, is it possible to increase that limit in 2020 too? That would at least allow me to use AU0322. Thanks.