Good luck on your all-thieves run, Corey! Do you plan to dual-class Imoen in BG1?
What exactly is this "level 1 protection" you speak of?
I started a new run, this time with a full party - all custom characters. Still playing on core rules and maximizing HP at each level. It should be way easier than my previous attempt, but hey, I need to get more experienced at playing the "no-reload" way (still doing lots of mistakes actually).
Main character is Alazar:

He is a lawful good cavalier who grew up reading knight stories. He's clearly not the clever type (some people would call him naive and trustful), but he's a nice guy. Specializes in bastard swords and sword and shield style. Since there is very few good bastard swords in BG1, he will also get a few points in long swords so that someone can use Vascorna.
Since he is a very easy-going and friendly guy, he gathered a bunch of "friends" who travel with him.

From left to right, first is Halyr. She is a true-neutral elven mage/thief who doesn't talk much, but shoots sharp and wields disabling magic.
Next is Vierna, a lawful evil drow (though, technically a half-elf) fighter-cleric. Reasons why she follows Alazar are unclear, and she doesn't like to talk about her past and why she fled to the surface. So far she's proved herself trustworthy and her divine spells will be crucial to the party's success.
Then comes Minuit, a chaotic good human sorceress. She has a raw talent for using magic, and especially likes fire spells... let's just hope she doesn't end up burning her own friends (she's a bit of a lunatic).
The brown-greenish guy in the middle is Alexeth, neutral good elven archer, Halyr's husband. Just like her, he does not talk much, but he's deadly with a bow. He also serves efficiently as the group's scout.
Finally, and the right end, the red-bearded Morkaï is a chaotic neutral dwarf berserker. Protected by heavy armor, he takes the blows for the group and likes nothing but to spill guts with his axe.
So far, the group was careful in their travels, journeying south to Beregost and Nashkell to do a bit of exploration in the nearby areas. Two assassins, Karlat and Neira, were vanquished without trouble. A party of dangerous half-ogres was dispatched by the heroes in a quick slaughter. Their most glorious win so far was against the mad cleric Bassilus, who was taken almost single-handledly by Morkaï, with the rest of the group offering support from a comfortable distance. We even met Drizzt, which seemed to trouble Vierna quite a lot.
Their most dangerous encounter was an angry mage at the Carnival. We seemed to have entered the tent in the middle of some kind of marital argument between this guy and his girl, much to his displeasure. Despite not being able to protect himself with mirror-image, he put the whole groupe (except Alazar, who was waiting outside, and Morkaï, under rage) to fear. Melf arrows and Larloch absorptions followed, slaugthering everyone but Morkaï. Once he had used all his spells, Alazar came in and both fighters eventually took down the madman, before rushing to the temple of Nashkell...
Afterwards, things went pretty smoothly. Characters have progressed to level 2 so far, with Morkaï and Alazar reaching their level 3. The Temple wolves were taken down carefully, even if the first vampiric wolf came a bit too soon: only Morkaï had a magic weapon at that time.
Next should be low-level areas in the region. The party will try their strategy on "parties with names who don't have mages or clerics", to get a few equipment and precious gold.