How do I decide whether to be worried about having enough blank pages in my passport?

I am planning a long trip over a year from now. The tentative itinerary is

• Canada
• USA (maybe LA, maybe Hawaii, doesn't matter, I have Nexus)
• Australia
• New Caledonia
• Vanuatu
• Fiji
• Samoa
• New Zealand
• Cook Islands
• Tahiti
• Easter Island
• Chile (or possibly back to places we have been before)
• Canada

I will be traveling on a Canadian passport. All of these countries are (for me) "you can stay 30 days without a visa" or "visa on arrival" except for Australia, which is an electronic visa.

In my past travels, some countries have been pretty good about fitting 4 stamps on a page (eg Bulgaria stamped on the way in and out, but they chose the page that the Netherlands had used for in and out.) However not all have been. Australia put their entry stamp on an otherwise empty page and then found a different empty page for the exit stamp.

I have three blank single pages scattered among the stamped-on pages, and then a stretch of 12 single blank pages running to the end. My passport is one-third full, then, and I have almost 3 years left on it. But I am a little worried this trip will fill it up. If each of the 10 not-Canada, not-US places consumes one page for the entry stamp and one for the exit, I will not have enough pages. But if they're more like Bulgaria was, I'm fine. Further, if travel from New Zealand to the Cook Islands and from Easter Island to Chile is considered domestic, there may not even be stamping involved for those legs.

It is not possible to add more pages to a Canadian passport. It is not normally permitted to renew less than a year before it expires, though you can request it and you need a good reason. "My passport is full" is a good reason. I don't know if "I have calculated my passport will be close to full" is a good reason or not. Further, I don't intend to spend long enough in any place to allow for the time it would take to renew my full passport and continue along my journey, should it become full along the way.

Bottom line: not just "should I be worried?" but "how can I tell whether to be worried or not?" Some specific subquestions:

• is there a way to tell whether a given country uses a 1/4 page standard size stamp, or glues a piece of paper into the passport, and the size of that piece of paper?
• is there a way to tell in advance which countries use exit stamps?
• is there a way to tell in advance whether trips between countries that belong to each other are domestic (eg LA to Hawaii will not generate anyone a stamp) or not - thinking of the Cook Islands and Easter Island for me, but generally applicable
• any specific advice about wildly early renewal of a Canadian passport would also be good