Hi,
Do you have any plan to make Flarum compatible with IIS and MSSQL?
I checked core repository and saw you use doctrine dal. I've no previous experience with this but theoretically it's support MSSQL. If you use doctrine query generator and didn't use raw queries then I guess this is possible.
On web server side, is it feasible try to use IIS? URL rewrite directives are looks simple and ISS URL rewrite module can be sufficient.
If you willing to support but need someone else step in to this please let me know.
Enver