Ready room

I am a member of the wedding party. Today is day before. The member of the couple whos party I am in just sprang on me that we will be using my hotel room for the ready room. I expressed discomfort with that as both my roommate and I will be also sleeping with our SOs of the opposite gender so there is a chance that one or both of them may need to come back to the room to change or something. My roommate shot my comment down saying that both our SOs (who are in the other side of the wedding party) will be getting ready together in a different room.

Im still uncomfortable with this as although the room is shared with another couple, this couple is extremely close with us and I don't personally know any of the other members of the wedding party.

I am fine with the idea of getting ready in a room together, i change regularly in my local gym locker room in front of other people. My issue is that my room is MY space. (Shared but still not for outside people)

To my understanding, normally there is a designated ready room. In addition, why do we need to choose a room that has people of the opposite gender? I understand they likely wont need to use the room, but just avoid the issue altogether by choosing a room only occupied by people of the same gender.

Tldr, is it inappropriate for the couple to ask someone to use their hotel room as the ready room the day before the big day? I feel like i have been forced into a position where i have to create a problem by saying no to this, but im absolutely unwilling to use my room for the ready room.