The right status (visa) ?

Please consider this as a hypothetical situation. I have no plans
as yet, only some ideas.

I am retired and of retirement age (and then some).
I do not plan to retire to Bali ...yet.
However I would like to lease land and build.
(The way I plan to do this, is probably worthy of a further post,
and may cause some raised eyebrows.) However that's for later.
It's my intention to live part time on Bali, part time in Australia.
Perhaps 50/50

What might be the best visa to go for ?

Without a doubt the best visa for you, under the circumstances you describe, would be a retirement visa. 

You can come and go as you like under that visa, but you must show permanent housing here, and you must return within 12 months of an exit under that visa. 

Lots of retirees split their time here in Bali and elsewhere.

Thank you, perfect !

I did try to check out the visa situation. God knows there's enough information
on this site. But I found with some you can do this but not that, and others
with which you can do that but not this.

Anyway thanks again. The only reply I need.