Compression fittings should be leak-tight.
Why the silicone hose? You could just permanently affix it through the wall with compression fitting to 1/2 inch NPT, through the wall with a weldless bulkhead, then a camlock on the outside.
I think this is how people set up HERMs for the HLT, you are basically doing the same thing.
Although it seems like an awful lot of work just so you can keep the lid on the kettle during chilling. Saran wrap always worked for me when I was being paranoid (otherwise I just 'let it ride')