Divinity Original Sin was amazing! The combat was fluid, and I highly recommend sticking with that combat mechanic.
I loved the way you had a set number of action points each turn to attack cast spells, etc (as well as more powerful abilities that could only be used once or twice per combat). In Baulder's Gate however, you have zealously enforced D&D long/short rests as a mandatory mechanic which makes combat and resting feel VERY tedious.
I get that resting IS an important mechanic in tabletop D&D, but in a game it's just... boring.
You can keep the D&D flavor of the world and setting (which I love), and encourage visiting your camp for the story line elements already in the game, but go back to the Divinity Original Sin 2 action point system and eliminate "resting" all together.
We should still have a "Go to Camp" option to regroup, heal up, chat with companions, craft, etc, which would be voluntarily used, but it shouldn't be mandatory to regain your spells / abilities. It's much too tedious.
As it stands now, I would rename the game to "Baldur's Long & Short Rest".
You have the game mechanics perfect in Divinity Original Sin 2. Don't throw that system away. Take that combat, and throw it into the D&D universe, and pow! You've got yourself an amazing D&D game that has the Larian Studio's flavor that we all love!