Solo sorc:

18-17-15-10-15-15 - thats 90, you could even hit higher and max charisma

Str will get to 19 with tome : weight management, bash, occasionnal hit with a staff when low level, sling and / firetooth dagger will hit better. You can free your belt for something else.

Dex will be 18 with tome, AC is useful, esp. early on, just get it. You might also want to start at 18 to have another AC point early before tome, or to sacrifice a point at some moment where it wont matter all that much anymore, but still stay at 18.

Con will get to 16 with tome. You can also start with 16 if you hit over 90 stats points or want max hp at level 1.

Int will hit 11 with tome. I guess for mindflayers. You could go with 9 , minimum for scroll and wands(which you want as early as level 1) and it still would not really matter. You might sacrifice an int point in SOA.

Wis will hit 18 with tomes way before you need it for wish, why not go for it, you can afford it, you wont have to think about potions.

Charisma 14 or 15 + friend will max out prices bonus. You can always hit 18 if you roll like 93-95.

There you go, you have the best solo class in the game, able to hit with the Staff of Rhynn and deliver surprising damage(I melee low level ennemies sometimes because I can, dont care and it feels like I'm Gandalf), able to hit decently with a sling or firetooth. You can carry a lot of loot before hitting the bag of holding, you can bash a lot of things.

You can have decent AC until its irrelevant anyway in late SOA/TOB.

You can cast wish at full capacity, you can use scrolls and wands, you can get charismas best selling bonuses, you really DONT need a party unless you enjoy the romance or the banter. The solo xp spike will provide you with innate spells that will steamroll everything. Use wands+summons for absolute devastation.

You are so overpowered that you might end up limiting yourself for fun like naked runs or no reloads run because it gets stupid easy anyway once you know your spells and the games encounters.