The game already contains the tools needed to make long rests less stupid.
Make setting up camp be an in game thing that you do. You can already pick up and set down things like barrels. Use the same technology on bedrolls. Or let players use bedrolls/rooms that they find here and there. Give each monster that is nearby a radius of %chance to find a party during a long rest, and bob's your uncle. Have the current camp instead be "Base camp" and make fast travel only work from one waypoint to another. This makes fast travel less absurd. Gives the NPCs that you don't have with you a place to stay, and lets you rest at reasonable places and times. It also encourages clearing out local monsters before trying to rest, or walking back to somewhere safe first.
Monsters in each area should also have some kind of alertness level/moral level based on how many of their buddies you've killed that goes up every time you take a long rest. There shouldn't be new respawns except maybe like, once a week or something, but more traps, and different patrol routes could work.
