Mikveh on the Eve of Yom Kippur during Shiva

If someone lost a close relative between Rosh Hashanah and Yom Kippur, and Yom Kippur cancels the Shiva period, can they go to the mikveh on the eve of Yom Kippur?

It is permitted to immerse even in hot water, an hour or two before the evening.

The Rema writes in Siman 606, paragraph 4: "One who lost a relative between Rosh Hashanah and Yom Kippur is permitted to wash and immerse on the eve of Yom Kippur, as Yom Kippur cancels the Shiva (Maharil on the laws of mourning), although it is customary not to wash for all thirty days, immersion for a mitzvah is permitted." In Siman 548, paragraph 10, the Shulchan Aruch brings a dispute about whether one who is sitting Shiva on the eve of a festival, where the festival cancels the Shiva, may wash before the evening or is forbidden until night. Practically, the Shulchan Aruch ruled that washing is permitted before the evening, and the Rema wrote that one should not wash because even during the festival, the thirty-day rule applies, and washing is customarily prohibited. Therefore, in the case of Yom Kippur, where immersion is more stringent, the Rema wrote to be lenient and allow immersion on the eve of Yom Kippur, as for a mitzvah it is permitted within thirty days, and at the end of the Shiva before the festival, he is given the thirty-day rule. The Mishnah Berurah in Subparagraph 24 writes that it is permitted even to immerse in hot water, and so writes the Reak"a in Siman 381. In Mishnah Berurah Subparagraph 25, it is written that one should not be lenient except an hour or two before Yom Kippur.