Joakim
If you haven't read this yet off of the old x2go website you might want to read about how Linux4Afrika Project configured their x2go servers.
That web site and information is a bit "dated" but it can give you some ideas.
One thing caught my eye in your email are a couple of your statements:
"the setup will serve 200 x2goclietn users on a wlan"
If the goal is to support 200 simultaneous users... I'm not sure those 2 servers can do that.
But if its just to support 200 accounts with some portion of those logged in at any one time then it can work but will still need some sanity scale testing by yourself
to know how many at any one time can be logged in.
Second, over a wan you don't say what kind of bandwidth your WAN has.
So basic questions will be what is bandwidth of WAN link to the site or sites.
How many users would be on each of those WAN links sharing that bandwidth.
Keep in mind no NX technology whether x2go, NoMachines NX or anyone else can defy physics so the size and number of Servers has to be
in line with the number of users and the load represented by the x2go server as well as any APPs they run.
The number of users will be limited at any one time to the bandwidth of your WAN link and the capabilities/size of your servers (cpu, memory, disk i/o, network i/o).