So, my friends suggested that i should make a proper web app to control the display, instead of just a single gateway page.
Basically i've nothing to change on my arduino code, i just have to develop a panel, and it would make the project more valuable, with added functionality such as sending custom message.
If some people remember my IoT weather station project, i've used a mySQL db, here i'll be using SQLite, i want to try to avoid MySQL. After reviewing my options for using a single file for data storage, SQLite seem a good choice.

Here is the scope of work for the web application (this log might be updated to add features)

Control Panel:

• Admin login with email and password. 
• Forgot password feature to reset login password.

After login, the admin can do the following functionality:

• Update profile and login information.
• Insert message into the database (message will be inserted in SQLite3 DB).
• View inserted messages list (all the messages will be retrieved from the SQLite3 DB).
• Add fixed message (ETH Balance).
• Message display settings page to choose whether a custom message or fixed message will display.

Arduino gateway:

• The gate will retrieve the last message from the SQLite3 database. If admin select fixed message option, the default message will be fetched from the SQLite3 database.
• The message will be rendered in the web page (<MESSAGE>blabla</MESSAGE>, nothing new here).

Security: htaccess to deny direct access to the database.

Technology: PHP & SQLite3, Bootstrap as theme.