I don’t think Miku will be able confess in that situation. Given that both Nino and Itsuki will be rushing over from Ichika side, and Takeda and Meada will catching up from behind Fuutarou soon, she’ll be surrounded just like in ch.78 but with the added presence of both Takeda and Meada, two people who she is not very close to. Couple that with exhaustion and the sudden turmoil by the revelation of Ichika’s schemes, Miku is not in any condition to confess right now so it’s best for her to wait for a more opportune moment in latter chapter in the trip.
Also, there is the matter with Meada that need to be resolve too. As he still believes that Fuutarou is dating Ichika, something that I could see Ichika take advantage of if he appears in the next chapter, to get some alone time with Fuutarou.