There are 20+ saver solutions posted on TiddlyWiki.com. The question is, how tightly is your system secured?
Can you run executable programs on USB (.exe) ?
Can you install executable programs (.exe) ?
Can you install extensions on your browser?
What websites are you allowed access to?
If you can install exe's and extensions, then the best solution is probably Timimi. It makes saving work like it did on TH.
If you can run portable apps, then tiddlydesktop might be a choice to run from USB.
If you can't do either of these, you might try the
TW5-browser-nativesaver It will display a confirmation dialog whenever the browser restarts, but the rest of the time works transparently.
If you can access Github, then you could use the github saver.
Another possibility is to run node.js on your phone, and use your desktop browser to access it. The problem is, everyone on your intranet could also access sit.