Tiny motor-homes and houses aren’t as sustainable and scalable as tiny apartments, as they will contribute to sprawl. If tiny accommodation isn’t available/legal near you, then a studio or the smallest apartment size for your needs is next best. Frugality is good, even Warren Buffett is known to have a fairly modest home.
If you rent, it’s pretty simple to try shared accommodation either by subletting if you have some spare rooms or moving into a place that offers shared accommodation. If you own, consider moving out and leasing the place and renting out a place that meets your size requirements if you live in a place that is too large, or relocating to rent in an area that is much cheaper, e.g. the country, an island or a city that is more affordable. Copy and paste into an online search engine “where in the world is it cheap to live?” and you will get plenty of results. This is what expats (a.k.a. expatriates) do.
Live in a place that is cheaper to live, while saving enough to buy a home or make a deposit for a mortgage and pay it off.
However, shared accommodation can have it’s dramas, see e.g. He Died with a Felafel in His Hand, the privacy of one’s own space can be advantageous for peace and quiet, etc.
House/pet-sitting / Caretaker lease \
If you don’t mind moving around a lot, then cheap short-term accommodation options may be suitable. House-sitting and these options can be a hassle / not worth it if you have a lot of stuff (and actually need to use a lot of stuff, e.g. for me: standing desk, monitor, laptop, lower desk for just above lap for keyboard and mouse, cooking gear like a pressure cooker, fermentation water-sealed crock pot, clothes, harmonium, bike, etc.). Such options include caretaker leases (a legal form of squatting), house-sitting, and squatting. Squatting is only breaking the law in Australia if there is evidence to show beyond reasonable doubt that you have broke and entered a place, or if you refuse to move when the owner or someone acting on the owner’s behalf asks you to vacate the premises. However, it is rare to find a place that you can squat in without breaking and entering. So even if you obey the letter of the law by breaking and entering without leaving evidence, you are disobeying the spirit of the law. I think it’s best to be a law-abiding citizen, unless there is a very good reason to break a law, e.g. with laws that are unjust. Plus with squatting and homelessness you won’t have electricity (unless you are using DC appliances and/or a DC-AC converter and battery bank with a car), so will need to go to the shops regularly, use a gas cooker, etc.
It’s not something that I recommend or advocate, in fact it’s probably something that is best to avoid for stability. One exception may be if you live in a warm climate. This is a site that may change your ideas about homelessness. Homelessness can be tough (perhaps less so if you live in a tropical climate that generally has comfortable temperatures most of the time), but you can drastically cut living expenses and give yourself an opportunity to have a lot of free time.
I haven’t tried homelessness myself. It would be more difficult without a car with being protected from undue weather and temperatures. It would also be difficult to have any privacy, which is desirable for meditation, so that distractions can be minimised.