If you know the specific URLs, that should work. Though I would recommend using a scoped bearer API Token rather than Global API Key: https://developers.cloudflare.com/fundamentals/api/get-started/create-token/ There are some rate limits specific to it, but yes it would work without upgrading to Enterprise. You can also purge the whole zone at once but I can see why this would be inconvenient if deploys were frequent!
Another potentially more expensive idea would be to have something in the Worker you can quickly reference (maybe a version in a KV value that is updated on build?) and compare to a header in the cache response to know whether that response is part of an old site deployment or not. But this would require reading from KV every request so may not be suitable depending on use-case.
Okay there isn't any separate paid URLrate limit I can share unfortunately, and yes there is also 1,200 request per 5 minutes but you can submit multiple URls in the same API request
I do agree that the tags would have worked much better if you were on Enterprise, don't have a lot of recommendations aside from the prior advice about having a version value somewhere which has its own problems