Sounds like a pro talking
The dental hygienist one works (I'd thought of it) because it's one of those things that's much cheaper over there and Thai dentists are at least as good as ours. Added to that, you'd have an excuse for not answering the phone. It's just a question of not being seen to be too eager to suggest it. I'll have to make my teeth look so dirty that she'll suggest it for me. (Ideally I'd use some fake stain kit with an antidote that I could apply before returning from the deed so it looks like something's been done!)
Minor medical procedures may work too (e.g. mole removal or something like that) but most have the complication that you need to show that something's been done. Or need something that she thinks will take ages but won't, giving extra time for play.
As far as I know, the wife's never thought about checking phone location history. You can't adjust it, as far as I know, just turn it off or delete parts. Would be nice to be able to change it because otherwise, if she looks, it's either missing for the day or there are bits unaccounted for if she really thinks about it.