In this package you'll find a 30 and 65 Deck Mod, plus some other stuff.^^
https://www.mediafire.com/file/zeu3trrqlouz60r/current_deck_MOD-bustyD-Totems.zip/fileDIY Method.
You'll need repak_b4b.exe + AES Key for extracting / packing PAK Files.
UAssetGUI for editing uasset Files.
From pakchunk30-WindowsNoEditor\Gobi\Content\MissionData you need those two files.
MissionDifficulties.uasset
MissionDifficulties.uexp
Open the *.uasset file with UAssetGUI and go to Table Info/Difficulty >> DeckLoadoutCards.
Set your cards there, f.e. 25.
Do this for all 4 diffuculties.
From pakchunk0-WindowsNoEditor\Gobi\Config you need DefaultGame.ini
Open the INI and search for "MaxDeckSize"=15 (set your 25 here, too).
Now just pack them again to my_mod_P.pak and my_mod_config_P.pak and you're done.