Creation of 3 always visible rooms until I decide.

Options
Hello, I have the following question regarding the use of Photon.
I want to know if it'd be possible to create 3 rooms by the press of a button,
and have these rooms always visible, even if they 0 players. I don't want these rooms erased,
only if I decide at some point.

The idea of my videogame is that before players enter my app, I want to have control of creating these 3 rooms,
with different scenarios and maximum number of players and leave them ready so that they only have access to just these rooms.

On each of these rooms I expect to gather around 64-100 players max. My game wouldn't be sending much messages other than player
position, photon voice and photon chat. Basically I'm trying to make a virtual expo or virtual conference.

I am aware about Photon SpaceHub, but at the moment I cannot afford the kit and would like to try to achieve it through Photon PUN.

What do you recommend for this kind of video game?

Thank!