Good tattoo artists are reluctant and dislike doing it because they are the ones that cover up hundreds of other people's tattoos who have done the same thing, and thought the same thing too. Professional tattoo artists want you to take away a piece of art that is very personal, permanent, and that you won't regret one day.
I'd rather just enjoy my marriage. Nothing needs to be written on my skin to do that. In terms of a visual cue, that's what the wedding ring is for.
But I think people set on this idea will do it anyway.