Get the bare minimum AXA visa Medical insurance. It’s quick, cheap and gets you in the door. Then work on getting a full policy. I wouldn’t touch Pacific cross.
I’ve not used one but from the forum they appear to run 4-8,000 THB. Of course you’d still have to pay the various fixed fees and fill the bank minimum
Good to start two years out. Others are right. Pollution in Chiang Mai is astonishingly bad and it’s a lovely area.
Get an agent to help out. Are you married to a Thai? That helps a lot. Especially if they have resident family as that gives you an address to use. If not - let the agent guide you thru the process.