Why would you be telling anybody that you're working remotely when you're just there on a tourist visa? As I understand it you'll have a Thai guardian Visa with a reentry permit and during that time you'll work abroad? The other thing is Thailand might ask upon entry why aren't you taking care of your dependants for months at a time.
A non O based on being over 50 is a retirement visa. Your next step is entering Thailand, putting 800k baht into a Thai bank in your name, waiting 2 months and applying for an extension
As others have said get the Non O based on being over 50, but get it before you come. Apply online with proof of 800K in your home bank, then transfer that 800K to your Thai bank. Choose your entry/extension date wisely as you will need to be in Thailand every year at that same timeframe to renew the extension.