I know this can become a dirty job, (probably defies H&S adherers , clean environment admirers, and annoys counters of gleaming rivets (!)
But, quite often any dedicated owner of a classic vehicle will be underneath doing things to it. One thing that will then not be far away is an "oily/greasy rag". Keep one old rag nice and oily, and use it, moistened by a small oil can of old engine oil , to wipe along bits that have just been cleaned. Gradually a good oily film will develop to supplement and refresh areas coated with waxoil. This will be a perfect coating for every crevice and corner.A Greasy film makes cleaning it all next time so much easier.