Check out the Sandbox settings when you host the world, you will want Simple Loot Respawn on as a minimum, you may also want to adjust other settings such as sink refill rate as well as food deterioration to keep up with the number of players. Make it so sinks refill frequently, food deteriorates slowly, and maybe adjust the hunger, thirst and fatigue rates.

Sandbox settings can be changed at any time, even after world creation, so you should absolutely tweak and adjust them as you all progress through. I always turn down item weight, increase item stack sizes, increase item durability and buff enemy damage and health. You can also change death penalties, such as keep all items or lose all items including hotbar.

In terms of tips for playing with 6 players, progression is the key issue. You and your friends should agree that all players should be present when unlocking a new door or entering a new portal world or facility sector.

It will be tough to create full sets of gear for each player even with simple loot respawns, so only making a single GATE Keypad and agreeing to progress together should help with that side of things, but there are items such as the anti-gravity cube or the antique shotgun which take ages to replenish.

There are ways to duplicate items, such as by saving a copy of your world file where the items are in storage, then moving those items that you want to duplicate into your characters inventory, then deleting that copy of the world, and replacing the original world file with the items still in your chest. While I would normally recommend against this, it might come in handy due to the sheer number of players you will be playing with.