Clam fest (qv https://www.urbandictionary.com/define.php?term=Clamfest) would be the most direct conceptual equivalent here, so would make sense even to those only familiar with the former term.
Examples found online:
their half of the island was a sausage party, while my half of the island was a complete clam fest,
Are most of this shows fans female?
28 y/o male here, and it seems Like it's a total clam fest, this fandom.
If I had known the [RPG] party would be a total clam fest I would have played a guy.
Not sure what sort of board gaming places you're going to, but my board game nights are a total clam-fest. At the very least we're a 50/50 split
We jokingly said she'd have to play a guy because our party was becoming a real clam-fest (we're up to 6 girls 1 guy).
My god the local game story is such a clam fest, as soon as guy walks in he gets swarmed by loud obnoxious gamer chicks.
Based on the quotes I found, however, this seems like it might be nerd-slang, used in gamer circles more than anything else. I only found one use not related to gaming:
Las Vegas Pool Party Girls: thats like a total clam fest ..that's what'im talking about
... and even that could have been posted by a gamer.
Unfortunately, we don't get much from checking the Google ngrams for "melon fest" (none found), "clam fest" (none found), "sausage fest" (started being used in late 90s), and "clam bake" (overwhelmingly popular for about 200 years, but impossible to tell whether any of these uses were referring to anything other than food).