You're a mad keen republican, and you've done everything you can intellectually to persuade the world of the silliness of a Constitutional Monarchy. You've argued, harangued, persuaded and nothing has worked. Why not expose it's flaws from the inside? Get yourself appointed as one of Her Maj's Reps and do everything you can to undermine the role. Start pontificating loudly about stuff you're not supposed to talk about, cause a stir by no-showing, with, I dunno, the Botswanans, get your Significant Other to act beyond their constitutional role... and see if you can't have a ready made home grown Constitution Crisis. It would be the best possible advertisement for a republic.
Any Harry or Tom can see that, and maybe even Dick as well.