Okay. I know I'm coming into this late but I find the premise really shortsighted. I've played two games where I have seen a rogue at the back do the following so I built my own.
Rogue: Cunning Action Hide around a tree, pillar, something... with an insanely high hide check. Per Crawford, hiding doesn't mean they don't generally know where you are. They just can't see you clearly.
Rogue: Attack with advantage since hidden (Can't see you clearly) and the rogue definitely beat the monsters usually terrible perception.
Rogue: DAMAGE!!
I brought a rogue in at 3rd level with a 16 dex. +5 to hit but with advantage and I do d6(3.5) + 3 + 2d6(7) so I'm averaging 13.5 a round at 3rd level. 20.5 damage at 5th and it escalates +7 every two levels from there. Those are some decent numbers at 3rd level and with the rate of gain increasing as it does, you can stay competitive however long you play that campaign. With nothing else changing you can expect 41.5 damage average a round at 19th level on a hit.
AND since you are rolling with advantage you are twice as likely to get a crit and fumbling is pretty darn rare. Crit damage on a sneak attack is sweet!