First, Nightcrawler posted an answer in the other thread. You should read that. What do you mean by dual-booting a USB? You want two operating systems on it? Or you want one operating system on it which you can reboot your computer into? (I suspect that's what you mean) Others may have different opinions, but I suggest going with Tails as your distro, which already comes with security apps (including Tor) and safe configurations. The Tails web site has documentation on installing to a USB stick. https://tails.boum.org/doc/first_steps/usb_installation/index.en.html