So I found out that Swiss Sys has a maximum number of rounds that can be executed in a single tournament of 24 (yes it’s a blitz). I am using an older version (8 something vs 9.1) but I don’t think it was changed in v9.
The USCF system, if you manually create a tournament in the TD/Affiliate area, allows for a maximum of 32 rounds.
Ah yes, now I remember. And it looks as though you’re still having trouble figuring out how to submit it for rating.
If SwisSys (and USCF) will accept 19 rounds, you could submit it as two separate 20-player (19-round) single round-robins. (Or perhaps as two sections of the same event.)
Or, as two 10-player double round robins (18 rounds, 9 double rounds) – top half vs top half, and bottom half vs bottom half – plus one 20-player double Schvennigen (20 rounds, 10 double rounds) – top half vs bottom half.
If that’s still too many rounds, you could even go for four 10-player (9-round) single round robins and two 20-player (10-round) single Schvennigens.