Tedious reading, overthinking things, it's really quite simple, get the 45 days when you arrive, please do the residence TM30 within 3 days of arrival in Thailand, either through a hotel or if staying in a residence, with the home ownership document, and their ID/Passport copy, then get your 30 day extension about 10 or 12 days before your 45 days expires, and you're right as rain. Enjoy your trip to beautiful Thailand!