What is the best visa option for an expatriate working offshore and living part-time in Thailand?

I am 44 and rent a house with my thai girlfriend, I work offshore in the UK on a 3/3 week rotation, so i dont ever overstay my 30 days visa-fee entry. I have been to thailand twice now this year and im told now that I will likely be refused entry a 3rd time.

My best option I think

I will get a SEV single entry visa for my next visit. This allow me time to arrange a DTV

After my next 3 weeks in thailand, as soon as I land in the UK I will apply for this as I will have the funds in my account and all the paperwork from my LTD company, payslips, contacts etc and letter from my company as a director to thai embassy stating I can carry out work remotely.

Is this going to be the right path.

If I then open a thai bank account and deposit 40000 baht a month into it.. I will use this to cover my rent and other things.

Will this be subjected to thai tax as its coming from my UK account and its earning from my salary that has already been subjected to UK tax. Im aware thst through UK and thailand have a double tax exemption in place in order to stop getting taxed twice.

I dont stay in tailand for more than 180 days at the minute but eventually I will reduce my trips offshore and spend more time at home

Interested in peoples point of view or advice

Thanks 🙏