I think the cipher system would function better if it counts a party of players as one unit.
So a full party who all offered 1 cipher would count as 1 entry with 8 ciphers, if a solo player gets the spot instead, the full party of 8 won't get in. This would encourage people to pre-form parties outside rather than go in solo and ask for a party inside since if each person in a full party offers 2 ciphers, that would be 1 entry with 16 ciphers offered and a solo player would have to offer more than 16 ciphers to enter alone. That would be a massive currency investment just to troll people, so it would cut down on that.
Plus, if one solo player can kick out an entire party, they'd be sabotaging their own chances of progressing by trying to go in solo, which would again encourage trying to get a party up before entering.