I got to page six before I realized that everyone who wants a party size bigger than 4 has this weird assumption that they need a tank, healer, rogue, and caster.
Guys, this game is based on D&D, not an MMO. You don't need to have a tank or a healer or a rogue or a caster. There are no tanks in D&D anyway! The closest you can get is a paladin with sentinel and a polearm, but that's it. I can't tell you how many times I sat down with two life clerics, or or two wizards, or three wizards (because everyone loves wizards for some reason). And you make it work. You solve your problems with the tools you have available. It makes it different every time because you don't have the same party every time you play.
The fact that so many people are spreading misinformation tells me they never played D&D 5e, which this game is based on. You don't need a rogue to pick a lock. That's just a DEX check. Being proficient with thieves' tools just adds your proficiency modifier (which you can get from a background, meaning anyone can get it). You don't need a "tank" because there's no such thing as AGGRO in D&D. Smart mobs go after the highest threat, which is usually the character with the LEAST armor. Dumb mobs go after whatever is in front of them. You don't even need a healer because Healing Potions are 50g and anyone can get a Medicine Kit. There's even a feat that allows you to heal with it. And lastly, you don't need any spellcaster because you can just buy SPELL SCROLLS.
For the record, I don't care if they party is four or five or six (though I'd prefer four). But don't spew this toxic misinformed nonsense saying you NEED a fighter, rogue, cleric, and wizard.
Honestly guys, go play some adventures league and then we can talk.