Even if you buy a cam visa as you cross, make sure they stamp you in as well. It cost me $us200 as they sold me the visa, decided my USD payment could be counterfeit, and demanded Thai baht, then put the visa in my passport but didn't stamp me in. When I went to cross back next day, they threatened to arrest me for being illegal. They wanted $400usd but bargained it down to $200 to get an exit stamp. Avoid Poipet
Singapore has had it for a few years. They have terminals in arrivals if you haven't done it beforehand, Thailand is complicated as they want to add money to an approved system, Australia have just about implemented a similar scheme as you get off the plane
How modern is you phone? Download an ESim from AIS or Dtac, sign up with the cheapest package they have, then login when you get there, and upgrade to the best data pack the suits you
My wife and I both have Thai Esims on our phones, both registered under her Thai ID, when in Thailand. We change the plan for the best value we need, then when leaving, change it to the lowest monthly rate, which is not much. They are good for 12 months if we forget to top up, then we just activate again on return. Both our home phones are Esims as well on our Google Pixels
My advice initially is to find out whether In fact whether you will be able to get a work visa as a "mechanic", if you are followed internationally, perhaps contact one of the racing organisations and offer to teach Thai,s your skills if they assist you. Otherwise I doubt whether will get a work visa. Only other way would be to invest capital in a new business startup. You will need to go the BOI for their rules
many don't realise that regardless of stamps in the passport, all the data is on the system, and they have algorithms that highlight certain types, a mate who does FIFO was interviewed at length, and after giving his work schedules they made a note on his file so he doesn't get queried again
Well done, I think it's a learning process for embassy staff as well, as most of them have only processed on fixed requirements, this visa they are making decisions, a very unusual thing for most public service employees