I thought I'd share my 60 day tourist e-visa process from the US. Saturday I applied online using the LA office. Monday I received an email wanting some additional documentation. ( I had not shown proof of exit) Today ( Wednesday) I received my e-visa!. They have a very quick turn around right now. They do require you show flights into and out of Thailand. I showed them a one way ticket in and a one way ticket to Cambodia at 85 days. I added a note saying that I planned to request a 30 day visa extension. It appears fine to show an exit beyond 60 but before 90 days.
TLDR : Answer Summary
A user shared their experience applying for a 60-day tourist e-visa from the US, detailing a rapid process through the LA consulate. They applied online on a Saturday, received a request for additional documentation on Monday, and obtained their e-visa by Wednesday. The application required proof of exit, which the user satisfied by presenting a one-way ticket to Cambodia beyond the initial 60 days. They also noted the potential for a 30-day extension.