There’s nothing stopping you from staying here (or wherever you are) and just fasting a few extra hours
There may be no Issur of fasting a few extra hours this year, but next year when the few extra hours shall be Leil Shabbos, this will not be allowed, so next year, the only way of feeling more anguish by an elongated fast without belittling Shabbos, will verily be, by going to the Southern Hemisphere.