How to use mobaxterm ssh/SFTP client with root files?

As I understood from https://unix.stackexchange.com/questions/111026/how-to-use-sftp-on-a-system-that-requires-sudo-for-root-access-ssh-key-based-a question there are not simple ways to use SFTP client with root stuff. I wish to use mobaxterm windows ssh, SFTP client login to Ubuntu server with keys. I log as user that has sudoer privilege. So I can elevate to root. the problem is that mobaxterm SFTP client doesn't have sufficient permissions to write to roots files. Any ideas and workaround for achieve the task?