The problem about resting is that we have to rest after every 1 or 2 combats... I don't have enough HP, not enough spell slots, not enough features... To deal with more.
I have a Ranger/Wiz/Warlock/Fighter in my party and I think I've long rested only 2 times and I've hit level 4, so I don't think it's needed all that much. There is a LOT of food around that you can use for healing.
Don't you use your wizards spells ? No offense but it looks more like a personnal challenge than a normal way of playing.
You have a decent team not to use them a lot and Gale's cantrip are very powerfull atm...
I also agree about HP and food, which is something like another exploit to me (you shouldn't be able to eat during combats).
But try to play with i.e a cleric instead of your rogue/warlock (or any other class that really need you to "long rest" to be efficient) and you'll probably notice that spell slot management is actually really hard if you don't abuse of the long rest.You can limit what you want, player's will still abuse the mecanics and that's probably because combats are often hard and/or needs us to spend many ressources.
I'm not against some sort of limitation or random encounters as suggested in this thread, but I really think that in the actual situation, it's just gonna be a huge constraint without any benefits (because i.e you'll have to go back in town to buy food supplly, not to rest less).