I tried online using the website for Bangkok immigration. I entered the information, hit the submit button and got a blank screen. I waited 40 minutes and checked and it doesn't appear on the approved screen.
I have tried a 2nd time and same thing . . . a blank screen.
A friend filed a 90 day report at MTT a couple of days ago he was there for 5 hours. When I went 6 weeks ago it took less than an hour. There is probably no predicting the wait time.
Thought so. Just want the OP to be aware of all the options. He mentioned insurance but did not give context. Often people are trying to avoid it if possible.