Why not get the O-A visa in the UK. This will give you multiple entry and if worked right two years before you need to apply for an extension. Also what you are asking isn't a customs issue it is immigration.

Matt Cogger the O-A is valid for 12 mths and everytime you enter you are allowed 12 mths stay. Hence if you leave and return just before the visa expires you will be stamped in with 12 mths permission to stay so basically you get two years stay out of the 12 mth visa. At the end of you last permission to stay period is when you then need to get the extension.

Yes Matt you do 90 day check in but that is much easier than a border hop every 90 days. The big advantage of the O-A is as Tod mentioned. You are stamped in for 12 months each time you come into the country.

Do as Tod mentioned, and get the O-A visa in Aust. It is the best option and as he said can be used for close enough to two years. That is exactly what I did and it worked a treat.

evisa and visa on arrival are totally different. An evisa is paid on application online, when you arrive you head straight to passport control, there is no further cost. Visa on arrival invloves an agent fee then payment for your visa when you arrive. Don't confuse the two they are very different.

Agree with Tod. Only way to get the 2 years is with option A.

Chiang Mai is the same certificate. Original for one license and copy for the second, but you must be doing the two at the same time.

What BS?