Thanks. Would be great if there was any official information available online, but there does not seem to be.
When filling out my visa application I was asked to enter a departure date as the visa is a 90 day visa. This is a bit confusing and can lead one to believe there is need for a ticket out of Thailand. I opted for the single entry as I figure I can change this when I get my 1 year extension. The email with my visa does state "Airlines may ask for the details of this e-mail so they can carry out checks to allow you to board the plane", so that in a way indicates that an onward ticket is not needed.