My understanding from assisting a mate recently with this problem....
There is a requirement to be resident in Australia for two years (for an Australian citizen), prior to receiving the pension while residing overseas, (assuming age requirements and asset requirements are met), especially if you have been working overseas for some years and not paying Australian taxes.
In your case, as in my mates case, provided you meet age and asset requirements on you return to Australia for 2 years in order to meet this 2 year Australia residency period, you will be able to get a pension within 2 weeks of arrival, plus social welfare benefits for the two years in Australia then continue with a pension payment on your return to live in Thailand until you croak. I am not sure if you get pension C.P.I. indexing after you return overseas. My mate took the opportunity (leaving his Thai/Aussie wife in Thailnd to mind the house), had several medical issues attended to cheaply, (ie, dicky knee replacement) , caught up with mates, and played lots of golf! and is now back in his rural home in Thailand.