Sorry, I am overcaffienated today, this response is kind of long.
"Data load?" Do you mean that:
a) handling lots of large files is too much for your computer to handle, or
b) simply having lots of large files on your hard drive (even if they are not currently in use) slows your computer down?
Because b) is pretty much impossible, unless you are almost out of space on your system drive. Which can be ameliorated by... buying another drive.
I once set up an install of InDesign on a Mac for a friend of mine who is chipping away at a big-data math PhD. and who is sick to death of LaTeX. (Can't blame her, really.) Because we are both BSD nerds from way back, she wanted to do what you are suggesting - but instead of thinking about aliases, which you are correct to regard with dubiousness, she wanted to do it with hardlinks. Which worked, more or less. She liked it. Seemed like overkill to me.
I suspect that this is because she is a highfalutin' academic whereas I am a production wonk in a business. I have to compare the cost of my time resolving a broken-link issue due to a complicated archiving scheme versus Just Buying Another Drive. Having clocked myself on solving problems induced by complicated archival schemes (or failure of overworked project managers to correctly follow the rules for same) I know that it doesn't take many hours of my work invested in combing through archives or rebuilding lost image files to equal Another Drive that I can go out and Just Buy.
If you set up a reasonable method of file organization, and document it clearly, then you have already saved your organization (and your successors!) significant amounts of time and cash. Hard drive space is cheap. Don't spend your time on figuring out a way to save a few terabytes here and there. In fact, what I'd suggest for you is to try to figure out how many terabytes you've already spent on this question, by figuring out todays ratio of easily purchaseable reliable external hard drives to your unit of preferred currency, then figuring out how many hours you've already spent on the question.
The only reason I can make this argument is that price-per-unit-of-magnetic-data-storage has, with remarkablly few exceptions, been constantly plummeting for decades, while the space requirements for documentation have been going up comparatively slowly. If you need a faster computer to do your job more efficiently, then price out a SSD drive for your OS and applications and jobs-on-deck, and then show your higher-ups the math that proves that the SSD pays for itself in your saved time within n weeks. My gut feeling these days is that, unless you are seriously underpaid, n is between two and six.
Finally: I didn't really address your suggested possibilities. Procedure C (placing PDFs) usually works, but you do need to figure out how to make PDFs in such a way as to ensure they play nicely with your print method. Procedure A (compress stuff you don't need anymore) probably works okay, but I hope that you have some sort of command-line scripting ability to be able to quickly route stuff into and out of archives.