5e isn't balanced for PvP. Use Spy instead of PC-class rogue. Tougher than 3rd level rogue, so it's got higher chance to escape, though the (non-assassination) damage is slightly higher too, thanks to better action economy (it's got TWF built-in into the multiattack action without the need to spend BA (so it can use Cunning Action at the same time) and adds ability mod to off-hand attack). However, it means it can get off a decent attack even if sneak attack is unavailable for some reason.