If you like the idea, then it is good. D&D in 5E is balanced enough that you kind of need to try to go wrong. The idea of the stealth paladin is a fun one - with the Avenger from 4E as a good example.
From an efficiency standpoint, your biggest 'hole' in your game is the reliance on a single attack per round. Everyone gets an unlucky streak, and if you miss on three attacks in a row, that can be three rounds in a row that you effectively do nothing other than absorb damage. You're also capping out at +2d6 sneak attack damage which makes the sneak attack damage minimally meaningful. You can get an average of +7 damage from a lot of sources - is the rogue really that essential to the build?
If you go with your build, I'd consider going with 2 separate one handed dex weapons at low level to increase the chances of getting a hit to deliver that sneak attack. You don't need to invest feats or anything ... just use the two weapons like most rogues do.
Personally, I would drop the rogue and go pure dex based vengeance paladin to level 6. I'd give them a Criminal or Hermit background to get the skills for a dex build.
Level 1: 2d6+3 (2 light dex weapons) = 10
Level 2: 2d6+2d4+3 (add divine favor) = 15
Level 3 and 4: 4d6+3 (divine favor become hunter's mark) = 17
Level 5: 6d6+6 (multiattack) = 27
Level 6: Can you pass on those charisma bonus to all saves, really?
From here you could add the 1 level of Hexblade for Charisma based attacks, and then either go with a bard or sorcerer build on top.
Note that this build also 'strengthens' if you happen to find a strength enhancing item more than your original build due to the multiattack.