I've been coming 10 to 12 times a year for the past 15 years, mostly less than a week, usually a couple of times a year 2 or 3 weeks. I bought a condo here as a holiday home, I live in a nearby country so this is my monthly break. Till last year I have never had an issue but now 3 times in the past 12 months they questioned me, usually asking if I'm living here, if I'm working here or if I rent my Condo. Often pull over a senior officer but once I explain why I'm here they let me go. Still it's unsettling and as many have said it's up to the officer when you arrive.
It was a BS thing, I had 2 friends ride 1150cc BMW'S to China, they weren't allowed to cross in because they were over 200cc, soon fixed by putting a 198cc sticker over the 1150 sticker.
local insurance was only about 500 Baht for 21 Days. It is pre covid I did this so it may have changed. You need a simple carnet to bring the bike out and in. You use to be able to do at the border. 5 years ago so you need to check.
You can go easily to Malaysia, Cambodia you can do but last I heard you have to go to a certain check point, and get an agent to arrange. Wouldn't even try Mynamar. Vietnam you can but there used to be some funny regulations about engine size, I think had to be less than 200cc.