By exploiting every bit of loot, I can get the "leather armor" (as opposed to "leather jacket") by my first visit to Klamath - not just one, but two. I also leave Klamath with a 10mm pistol, and over 200 rounds.
It's all about squeezing every drop out of what is offered to you.
But what you're doing is clever enough - although I would let Sulik keep his armor, because, hey, it's armor - he needs it!
There is a stick of dynamite in the rat-tunnels below Klamath. If you have a high lockpicking skill, you lockpick the door next to it, instead of blowing it up - and tada - dynamite for you! Whatever on earth you need it for - you have it now!

There are, afaik, two books in Klamath, one gun-book in an empty house just near the entrance, and then a survival-book on one of the kids over in trapper-town.
Klamath has lots of nice free loot to steal or lockpick, which is practical for early boosting.
And why kill the shopkeeper? Just help Lara's gang defeat Metzger's crew outside that church, and you have plenty of handguns to trade.
I will often use my steal-skill in the start of a game, to give my character an edge. By stealing and lockpicking eagerly, like I said, you can leave Klamath with a companion, both of you suited up with leather armor, armed with 10mm pistol, and I will typically leave the Den with a hunting rifle instead of the pistol, and by then I stop stealing, because you will practically be showered in loot to trade. Just be patient, and snoop around!