Charisma doesn’t help rouges in combat at all so it’s probably a waste to put more than a couple of points there. However you could make up for that by putting proficiency in a couple of the talky skills, especially as rouges get to turn some proficiencies into expertise (2 at the start, and 2 a bit later). 12 charisma would probably be fine, you could push it to 14 if you really wanted, but that’s only an extra +1 to talky skills.
So for instance at level 1 you could be proficient in slight of hand, perception, deception, performance, and expert in stealth and persuasion. With only 12 cha, you get +3 deception, + 3 performance and + 5 persuasion. With 16 dex, you get + 5 in slight of hand and +7 in stealth. Or ditch performance and add acrobatics if you don’t want to loose your cool (and your turn) by falling on your arse too much, or whatever.
So you could be a charming assassin ninja and very respectable lock picker if you want, but I wouldn’t try to do it by putting a load of points into charisma. If you want to get to ridiculous levels of speech skills though, put aside you aversion to the magics and embrace being a versatile lovable dick.
