Please clarify: is your pool 36,000 gal (per post) or 24,000 gal (per signature) ?

I would not go with cal-hypo in a vinyl pool.

Have you checked with the pool stores in your area to see if they carry liquid chlorine in 5 gallon carboys? The concentration is 14% when manufactured but degrades to around 11-12% during storage, still twice what regular bleach is. I pay around $15 for a refill in my area. You'd have to add approximately 1/2 gallon daily to keep your FC at a minimum of 3 ppm.

Depending on how much longer your pool will stay open you might be able to augment the chlorine demand with trichlor. Yes, it does drop the pH and increases CYA but if you don't make it your primary chlorine source those changes will be relatively minor. You know how to raise pH and bringing the CYA up a few more points won't be a tragedy this late in the season.

Having a pool means having to add its maintenance expenses to our annual budgets. If you're shooting for "cheap" you will eventually get what you pay for and then you'll pay for cleaning up what cheap created. Testing the water and adding some chlorine every day isn't much of a hassle though I agree that buying bleach in gallon jugs and having to dispose of them can be inconvenient when you have a large pool. Try to find the carboys, they make life easier.