KJ & AT in an unopened pot in LP is a big hand imo, on my ubuntu laptop atm so cant get stats. Like a prev poster has said, i'll isolate with it all day long, and might even open from MP if the tables (specifically the blinds and those IP on me) tight.
I really think you need to play some 6max fx just to get some more practice in marginal post flop spots, if your not opening KJ from the HJ b/c your scared of playing TPGK thats an issue imo. Like if you have nailed down stats that say your losing when opening KJ in LP then you need to look at those hands and figure out why its a loser, rather than dropping it completely.
Just read the last bit of the above post, its good that your trying 6max, i'd recommend at least 1 session per week, play 2-4 tables tiled and really get to work playing postflop and exploiting people based on solid reads, read fee's 6max guide if you havent already.
If nothing else it will make you more comfortable playing in unopened pots from say MP, as then its really just like 6max UTG, cept you'll probs have more nittier people to your left, making it easier to play as they are mostly playing faceup.