What documentation do I need for a visa-exempt entry to Thailand as a Canadian traveler?

Just come overland if you feel that it's going to be complicated satisfying airline requirements. It's really not far and backpackers are used to it.

If you're in Ho Chi Minh, catch a bus to Phnom Penh (5-6 hours), there are around 30 or more daily, operated by several different companies.

Spend the night then look for a direct bus to Bangkok, which leaves once a day.

An alternative is to find a bus from Ho Chi Minh to Siem Reap. There are fewer departures, but still several daily, though it's a longer haul (could take up to 12 hours). Then from Siem Reap, you have several daily direct buses to Bangkok (7-8 hours including stops at the border).

You can do this journey more quickly by taking taxis along some parts of the journey. I've done Phnom Penh to Poipet in less than 5 hours for instance. Aranyaprathet to Bangkok, can take as little as 3 hours.

use Onwardsflights dot com> worth the few $$ for peace of mind

If you do use Air Canada that is a definite..book an onward ticket just before expiry to satisfy departure...(online temp reservations can be found by google search for exactly that.."onward travel". Suggest you avoid online pre checkin since, at least in AC's case..they will request a visa and there is no provision to input anything like a visa exempt status ..and raises flags. However, with an onward ticket reservation and your flight locator # you should be fine..and when you arrive in Bangkok you should sail through with 30 day visa exempt but wise to have a hotel reservation to satisfy TM30 requirements...something you will find out about should you apply for an extension in country later.

Yes you get 30 days visa exempt entry.

The technical requirements are: 20,000B (about $800 Canadian) or equivalent in cash, proof of accommodation booking for duration of trip (normally first few days is fine) and onward ticket leaving Thailand within the visa exempt period.

99.9% of people don't get asked anything by immigration and just get stamped. Especially holding a Western passport. Your airline is likely to ask for proof of onward travel though.