I guess Thailand humidity is very high, so the temperatures there FEEL way worse than what they are, because the humidity prevents you sweating to cool down.
I also lost a lot of weight, but I mostly did it by eating less, rather than exercising. It is very hard to keep the diet regime going, because of temptation, but I'm just about managing.
I know you were thinking of Vietnam previously as a possibility, and I think that is definitely cooler than Thailand, especially in higher areas, but maybe you don't want to be remote like that.
I hope you find a new home soon. Wandering the earth like Caine, in "Kung Fu," must be hard for you.
And of course, you gotta keep an eye on rabies laws in various places, because some places, like Britain for example, will force animals into quarantine for 6 months in some cases.
Enjoy your break in Oz, and good luck. :)