How to create iRule to respond with Maintanence Page for HTTPS site

It will never work without the BigIP terminating SSL because in order to read or write http headers, you need to decrypt the payload. If you need SSL encryption on the serverside connection, you'll need to decrypt the client-side connection using a clientside ssl profile, then perform http operations using an http profile and iRule(s), and then re-encrypt serverside connections using a serverside ssl profile.