dynamically change Tampermonkey script in Safari

Question

How can I make dynamically changed user script using Tampermonkey in Safari without actually open Tampermonkey and edit some code manually? I want to change the contents of a script on the fly. I used to do this in Chrome with @require attribute pointing to a javascript file in my file system. Then I programatically changed that javascript file accordingly. Worked like a charm. This doesn't work with Safari, due to it's security.

I tried manually changing the /Users/mainuser/Library/Preferences/com.apple.Safari.Extensions.plist file, but that results in corruption of Tampermonkey, since Safari doesn't like to see users changing it's preferences manually. It does some checks to see if someone tempered with it. Don't know which file should also be edited to avoid this. So the question remains, how can I dynamically change content of user script in Safari?