Hi leg3nd, good job.
Take a look to this repo: https://github.com/xtr4nge/sslstrip
Response tamperer support (@kkotowicz) and Code Injection was implemented (@xtr4nge) in the same SSLStrip fork.
Options:
-t <config>, --tamper <config> Enable response tampering with settings from <config>.
-i , --inject Inject code into HTML pages using a text file (default inject.txt)
For code injection you can use the -i option and the file path, so you don't need to use the hardcoded file path/name.
Also you can implement more advanced attacks using the -t option.
I'm adding these functionalities to my project this week.
regards,