OK. Imagine this: Crash on beach. Fight devourers. Multiplayer 4 players. Player 1 lost 4 HP. Player 2 lost 3. Player 3 lost 7. Player 4 lost 5. Level up!
Tool tip pops up: "Short rest can be done at any time, as much as you want, by pressing the Short Rest icon. This will fast travel you to one of the camps for safe resting. Short Rest costs 1 Camping Supply per point of HP you wish to recover - minimum 1 Camping Supply per character. Each character spends Camping Supplies individually and can spend as much or as little as they wish - minimum 1. That character must either have Camping Supplies in their inventory or in their own personal Traveler's Chest at Camp. In Single Player Mode, all characters share the same inventory and Traveler's Chest at Camp. Short rests also reset various class spell slots and abilities. For example, the Warlock has all spell slots replenished after every Short or Long Rest. The Fighter's Action Surge and Second Wind and other later abilities, the Druid's Wild Shape, the Cleric's Channel Divinity powers, and the Monk's Ki also reset after a Short or Long Rest. Besides this, a Short or Long Rest is required to Level Up your characters, a Wizard can use Arcane Recovery ONLY during a Short Rest to recover some spent spell slots, and many dialogues are only triggered during a Short or Long Rest."
"For Long Rest, all abilities and spell slots are reset, and all HP is restored. Many conditions applied to your characters will also be removed during a Long Rest. A Long Rest ends the adventuring day, meaning your party is resting for the remainder of the day and starting again in the morning. Long Rest costs 5 Camping Supplies per Character Level at the Camp. So, if you have 2 characters at the camp at Level 2, the cost is 20 Camping Supplies (5 x 4 Character Levels). If you have a party of 4 at Level 2, the cost is 40 Camping Supplies (5 x 8 Character Levels). The cost is steeper because of the additional benefits of Long Rest."
So, with our example, each player gets the Camping Supplies window and chooses how much they want to heal up during a Short Rest. Player 1 spends 4 Camp Supplies in his own inventory to heal up to full health. Player 2 spends 3. Player 3 spends 4, leaving 3 HP loss. Player 4 spends 3, leaving 2 HP loss. Players exit camp after Short Rest, appropriate abilities are reset: such as Second Wind, Warlock Spell Slots, etc. As the Wizard is exiting camp, she is asked, "Do you want to use Arcane Recovery?" If Yes, the Wizard can then choose how many spell slots from their maximum Arcane Recovery pool, that they wish to recover. So, at Level 2, the Wizard could recover 1 Level 1 spell slot. In options, a player can turn off the popup, choosing to trigger Arcane Recover themselves during a Short Rest without having the reminder - if they feel it's annoying.
Later, players choose to Long Rest after fighting their way past Mari and Barton and company. They now have Party of 4 customs, Shadowheart, Astarion, Gale and Lae'zel, because they picked up Lae'zel before going to the crypt. Hmmm. Do they really need to keep all these characters around? The cost is going to be 5 times he total Character Level. That's a steep price for characters they will NEVER use because with a Party of 4 customs (based on present game anyway), they can NEVER take any of the origin characters in their party... ever. So why keep them around? They'll just leech off of you. So, you take a Long Rest and boot those puppies from your camp. Camping that night for a party of 4 Level 2 characters would be 40 Camping Supplies. If you keep the others with you, it's 80 Camping Supplies. Yeah. Time to boot the excess baggage.
The basic Camping Supplies cost for Short Rest severely pushes players towards Short Rest while the higher cost of Camping Supplies for Long Rest discourages frequent Long Resting. As a party, if I need to recover 19 HP and my abilities and some spells, I can spend 19 Camping Supplies as opposed to 40. At later levels, this becomes even more pronounced as the cost for camping during Long Rest would be even greater. 4 Level 8 characters would be 160 Camping Supplies per Long Rest, but if you only need to restore maybe 30 HP as a whole party, that would be only 30 Camping Supplies for a Short Rest; a considerable difference. And, if they do actually listen to a lot of us and increase party size to 6, the costs become even more. You might spend 40 Camping Supplies for a Short Rest for a Party of 6 Level 5's, but 150 for a Long Rest.
Maybe 5 Camping Supplies per Character Level is too much for some players. Provide a Long Rest Camping Supplies Cost slider that reduces the cost from 5 per Character Level to 4 or 3 - 3 being minimum so there is at least SOME cost to Long Resting that would maybe still encourage Short Rest at least a bit more frequently than Long.
With Tool Tips that explain the details more, and are worded to encourage Short Rest more than long, and with Camp Supply Costs being less severe for Short as opposed to Long, players would be far more inclined, I would think, to Short Rest more and Long Rest less. It also encourages players to boot party members they aren't using or don't plan to use. It makes camp management a bit more immersive, and it makes food you pick up A LOT more valuable. With as much food as they're dropping currently in the game for players to pick up, this would truly be no big deal. You could likely Short Rest multiple times in the beginning and still Long Rest a few times before reaching the grove.
And, I almost forgot to tweak this idea a bit from previous mentions of it. No cost for extras in the camp. Yeah, upon further consideration, Volo, Scratch, Halsin, Owlbear Cub, etc. shouldn't cost a thing. If you aren't taking them with you to adventure, restoring their HP or spell slots, they shouldn't cost a thing. Let them find their own food.