Chiang Mai to Laos they started insisting on a 1 night hotel stay outside Thailand recently - that came from the Thai side. Somebody is getting a fee :-)
It depends on the crossing. I do not know which ones the guys I know go to but they drive themselves from Jomtien and told me the cost had doubled. I think when you go on an organised bus it is included in the total price. I had to do one last year going from a BOI "B" to a O Retirement as needed a Visa Exempt in between. It was pretty obvious tea money was in play both sides of the border.
Just as they could make it "Tricky" for an ED to re-enter ie talk to us in the Thai you have been learnig for 2 years. Could Immigration not ask for ongoing proof and DTV qualification ie show us your medical appointments, where is your receipt for your next course?
It somewhat "Breaks the rice bowl" of Immigration though. The DTV was a Ministry of Foreign Affairs idea and it is they who issue it. It is Royal Thai Immigration who own extensions and re-entry. When the Visa Exempt was increased from 30 to 60 days the same day border crossing "Fee" doubled from 500 THB to 1000 THB at some crossings. They like to make sure their rice bowl is not broken. :-)
I am talking about under 50's as once you hit 50 the current retirement visa is easy. Many have lived here longer on various visa types. They used a mixture of various tourist and Ed visas etc. I remember when people would do monthly visa runs from Bangkok to Poipet. The DTV makes all of this easier.
Good luck with it. Different Embassies and Consulates have different requirement. I know people who have used their Limited companies in London to get the DTV. Shown company papers that indicate they are owners. The tax return of the company. A letter as owner to themselves as owner stating they can work remotely from Thailand. All approve in a straightforward manner.
Business if you are applying using your LLC. It shows it is active. As the owner/Director you can also write a letter to yourself as employee stating you can work remotely from Thailand too
That is def what I would be doing until the lay of the land becomes clear. Take the opportunity of cheap regional flights and have a holiday in the region.