Boot off usb, especially with a slimline flash drive. Backup with rsync, onto a network share/ssh server which gets properly backed up. Alternately take note

Boot off usb, especially with a slimline flash drive. Backup with rsync, onto a network share/ssh server which gets properly backed up. Alternately take note of how Elliot of the Mr Robot series works if you need further inspiration, the general overview of how he uses his pc is very close to what you suggest as he destroys his workstation regularly to avoid forensics.