Chaos: You can set Fisher's clock to e.g. 25/0/25 what means no added time, just 25 days for both players, but it means bigger problems wit time zones.
And for pawns I would rather recommended round robin - more games in one tournament
(hide) If you want to play a game with an opponent of a similar level, you can define a required BKR range for a new game invitation. Then nobody with a BKR outside this range will be able to see/accept it. (Katechka) (show all tips)