Archipelago: tribute + buy units = win?

So I was playing an Archipelago game as Carthage (Emperor, Small map) and found an incredibly effective strategy that seems rather exploitative: build 2-3 ships (quinqueremes in this case), ask for tribute from 2 CSs, use that to buy another ship, ask for tribute again, and so on. Granted, I usually play on Immortal and usually don't play on Archipelago because it's so much easier, so this might just be a one-time thing. But I feel like it would probably work on Immortal, considering how inept the AI is naval-wise (although it has improved in G&K).

So, thoughts? I'm gonna boot up a Deity game in a few days, but is this do-able on Immortal/Deity?