The Mysteries of the Tent Screen

Sounds like you got everything working, but here's my understanding of how that sequence of events works.

When you enter the Blackjack when it's grounded ($1EB7.2 set), the game jumps to an event at CA/0059. This event address is hard-coded at EE/B26F and loaded by bank EE code here:

Code:

EE/2092: AF 6F B2 EE  LDA $EEB26F     ; CA/0059 (enter blackjack, ground entrance)
EE/2096: 85 EA        STA $EA
EE/2098: AF 70 B2 EE  LDA $EEB270
EE/209C: 85 EB        STA $EB
EE/209E: AF 71 B2 EE  LDA $EEB271

Here's the event:

Code:

[ Blackjack Ground Entrance ]

CA/0059: B9        If ($1E80($09D) [$1E93, bit 5] is set) and ($1E80($09E) [$1E93, bit 6] is clear), branch to $CA5AD4
CA/0061: D2        Load map $0007 (Blackjack, below decks, all rooms except Celes' prison), position (08, 35), mode $00
CA/0067: FE    Return

The event at CA/5AD4 loads map 3 and places you on that event trigger:

Code:

CA/5AD4: C8        Set bit $1E80($02BD) [$1ED7, bit 5]
CA/5AD7: D2        Load map $0003 (Darkness (briefly on many occasions, inc. Tent use on the world map)), position (08, 09), mode $C0
CA/5ADD: FE    Return