You can do it until the officer you get decides you are breaking the “rules”.
Normally when they think you are living in Thailand, especially if they suspect illegal work.
That could be as soon as the 2nd (possibly even first) and could be years and years in a row. That would be rare without “help” for border runs but technically possible.
The officer you speak to along with their supervisors can do whatever they think is right. Most will be warned not outright denied entry first.
TLDR: you realistically can’t live on visa except entries unless you have “help” with border runs.
If you plan to stay beyond 6 months a year it makes sense to look better visa options. The new DTV is perfect for many who want this but lack the funds or desire to pay for the elite/prestige.
You might be able to fly to South Dakota, stay in a hotel and open a mailing address and get residency and thus a new U.S. residency and DL.
That would be 100% legal under SD law. At least for us citizens. Not sure if it would work the same for UK citizens but since you have a NV license I would guess it would work.
I would suggest visiting other similar countries first.
One can be a long term tourist in some (Philippines is basically forever) while being nomadic between several keeps you within the rules of being a tourist in others.
Yes there are ways to stay in Thailand long term before 50. Some are grey area and some are 100% above board.
But until you have experienced several countries and areas within each you really can’t know what you like or don’t.
Given Thailand doesn’t want people living there on the wrong visas it is worth traveling more to be sure you want to put in the effort.
Once you are 50 as long as you have the income/assets it is relatively easy to stay in Thailand.
Before that why not not make sure it is best for you?