Thanks for all the helpful, thoughtful replies.
As far as Puerto Rico, that's an interesting thought, but we are specifically attracted to SE Asia and especially Indonesia. Among many reasons, we want to be close to all the major durian countries to eat durian cheaply and frequently. We already own a small rural lot (1 acre) in Hawai'i and it's quite nice here in many ways, but we were thinking we might prefer Indonesia and be semi-retired very soon, by which I mean pursuing hobbies more than business. We are workaholics with some entrepreneurial ambitions and want to stay involved with intense physical labor (gardening/landscaping) part-time, not looking for any kind of condo/beach/TV lifestyle. Our cost of living is very low in Hawai'i, but I think it would be far lower in Indonesia, allowing us to focus on passions/hobbies more than income/survival.
Haven't been to SE Asia at all yet. We're planning to visit various SE Asian places as soon as possible in the next few years, but since it's such a vast region, we're thinking in terms of choosing places to get familiar with that have potential as long-term homes.
This is a dumb question probably, but I couldn't find the answer anywhere I was reading up on Indonesia visa stuff. If you do the 30+30 tourist visa, can you leave for a day and come back for another 60 days and keep repeating that indefinitely? Or can you only do 60 days per year? Could you live on Borneo and go to the Malaysian part for a few days and then go back to the Indonesian and start a new 60 days? (Or vice versa, if anyone happens to be familiar with Malaysia's version of the visa laws.)
The idea of flying around to different spots in SE Asia every 60 days actually seems very appealing, like a nice rhythm of exploring the region, but having a home base and a garden. I was imagining someone in a rural part of Java would be thrilled to have a long-term tenant just as a source of income.
When you talk about rural Java, you need to comprehend the insanity of the place when it comes to getting to & from immigration offices, etc.
I live in a kinda rural area yet am just 15 minutes from KanIm(immigration office), I used to live best part of an hour away and it used to be extremely complicated for me to get there without my own transport, so you would need to consider how you would travel to & from the place & how it feels when you have waited a while to do processing to be told you need another document ... that you may or may not have but it is back home on the kitchen table.
The above is quite the norm or was pre online visa stuff.
Re transport how do you intend to get about? Many rural areas have signs up strongly advising GoJek/Grab drivers not to enter, as it puts the local ojeg/k out of work- a bone of contention there.
If you intend to have your own transport, that has its own issues, not least the driving licence- the place I have to go to for mine is 2 hours away (or was until they built a new toll road - now cut the time to 40 mins - ace!)
Then there are the questions & hassles around ownership documents etc.
Then there is the whole thing about having an empty house whilst you are off travelling elsewhere- we NEVER leave our house empty, because we are in a village and not behind the walls of a (ahem) secure complex.
The 'secure' complex near us is the place that gets bikes stolen from it.
We to date have only had chickens stolen & that was before we had garden walls & gates on.
I like the idea of growing my own food and we grow a few basics easily such as tomato/chilli/fruit/tumeric/ginger etc- I asked my hubby about growing areas in Java for durian , he suggested central Java.
IF you intend to work whilst here, be it online or physically then you would need to meet certain criteria - if you spend any longer than 180 days in the country in any 1 year you have to register for a tax code.
If you are on a reasonably large plot and are creating produce that could be construed as agricultural work you need to be aware of the likelihood of having to explain it to officials when they come calling they will not take kindly for example to you selling the produce. On a tourist/visitor visa that is exactly what you have to be- a tourist/visitor, not a cottage industry

They most likely will come calling have your explanation ready.
Also you would need to consider the stability of the land, its proximity to active volcanoes and other such specifics, one of the main issues around the rural parts of the islands is landslides.
I am trying not to be too negative as I live here & LOVE living here & can completely understand the appeal, I just wanted to share some of the absolute realities of living outside of the apartments/ complexes of the big cities.