Adding HTTP proxy to Tor Browser

What is best way to add local HTTP proxy to Tor Browser ? I noticed that i can’t add proxy like in Firefox in network settings.
I want to add burp (local http intercepting proxy).

Also can i just copy .tb folder and have another TorBrowser to experiment or i need to do something different in order to have second TorBrowser ?

Depends if local or remote proxy.

Related:

Yes, see:
Whonix-Workstation Security Hardening - Whonix

easier and safer: