sure you can.. But the fact is 90% of the deals for this kind of short term accommodation dont go online.. The market is too fluid, the margins low and the best deals done by people that dont have email, internet, web publishing etc skills.
About the only real estate agent that can be bothered with the rental market is welta
Hello, my name is Wellta, I'm born in Phuket: houses on my island.
I also know 2 girls who are (talkign about) starting up a house hunting and room finder service in the tourist towns (Kamala, Patong, Karon, Kata) looking to the budget / guesthouse market..
My advise is arrive with one week guesthouse and spend that week looking really hard..