Can you tell me which are this outfits in the 1st map clear you may miss? can only think this are the maid outfit but that one you can obtain any time really, specially if you do the Alt - Z cheat in the simon says game, most of the outfits are obtained in HARD mode, and those are re-doable.
the only ones that may give you issues i can think of from the top of my head are:
-The wolf outfit in her forest as the enemies are really powerful if you are low level, thinks is one thieve, and 3 larva-raise
-The ones you need to kill two Necromancers in the 2nd Rebeca level, they throw meteors.
-The one you can only obtain by using snipe shoot on a sand dragon (he has only 3 HP, it can give you issue if you don't have the sniper ability, because you NEED this ability to kill the desert dragon, monsters who can learn this ability are the Alkibana, horned fluff and think crossbow thieves, also Peer can learn it...)
- And for me the hardest one is the Sheilas panty outfits you can only obtain by NOT killing ANY of the white apple dogs who fight you in the dungeon cave level, they all are lvl1, you kill or capture just one and the NPC wont give you the panty item you use on Sheila. I guess you can capture them, not sure, i capture one who was going to be killed by the NPC so he not die and still got the pantsu item at the end... but better is not risk it to find out... Again this are Hard mode and you can redo them till you manage to acomplish all the requirements.
Pretty sure the only miss-able outfits are the ones in the 9 maps, as this are story battles and are mostly hidden in chests. Got to say this are the most depraved ones if you ask me ^//-//^U lol. i love this game.