I imagine this visa will never be as popular as it is right now in its first few months.
The number of people that can live in another country for 6-12 months is very, very small.
90% of people take two week to four week vacations once a year.
In fact, I don’t know anyone in real life that can easily move away from home for 12 months - only the people I meet online in nomad style communities.
So over the last 5 years, I've been in Thailand around 9 months out of 12 each year on tourist visas.
And when I applied for the DTV, I included my employment contract, the invoices I'd sent my client for past 6 months, and a screenshot of my linkedin where every role has the word 'remote' under it (and I believe I have the word freelancer in my title). And I had no issues.
So those are just some ways to cover your bases - as they're looking for evidence you're a remote worker/freelancer (unless you own the biz)
I don’t think that’s a good idea. If your clients are from overseas just show enough proof that it’s easy for them to see that.
If you start making them think about ‘not working from Thailand’ they may want to question you further about why you included it (they may not even think down that route if you don’t mention it)