What is the appropriate version for my game


I am very new in multiplayer game, (I always did single player server less games).

The game is a RTS in Unity with a persistent map where player can build army, move from point to point, build buildings and attack other players. The map is the same for everyone, user can send attack and those attack take x amount of real time to arrive at destination. So since I want a persistent world map, I Would like to make a game where there is a SINGLE server where the game state is unique.
So, I believe for my need, a dedicated server, that is permanently running, even with 0 user connected (since when a user attack another one, there is a travel time, and when this user disconnect, the server must keep calculating the travel time of the sent unit) is what I need.

Now, I am looking to all the offers that PHOTON grant me, and I am a bit confused.

Should I use Photon Server => I like the fact that I can start from a base and make everything by myself, but I read. Photon Server does not provide a persistence layer. Is it something that will impact me? Is it hard to build ?

Should I use PUN => It's made for Unity, so it sound like the best solution, but it's in the cloud, and the architecture require master server / slave server with multiple rooms, but in my case I would like just a single server, and a persistent room.

Should I use something else ?