I always thought lean guys had it easier IWB as well. A very slim buddy of mine has no problem carrying his Glock 27 IWB, while I had to opt for the Walther PPK/S, and now the Kahr P9 due to the extreme discomfort I felt IWB with a 27.
The only IWB that is comfortable (while standing) is SOB. I think a good belt-carry SOB would be even better than IWB, but A drive in the car is QUITE uncomfortable, not to mention that your piece is completely inaccessible! I had to opt for the "Uncle Mike's" because leather was WAY too uncomfortable. Nothing IWB works for me on the hip, but then, I'm not anywhere near the "lean" category
I also can't see me going out and buying all new pants to fit my carry gun in, that's just too expensive. I'm sure it would help some though.
I tried the "Smart Carry", and it was too obvious, but comfortable. I've just recieved "Gunslinger's BellyBand", but it's a rightie, and I'm a leftie, but it has potential.
Lastly, a relative of mine, BIG guy, HUGE!!! (6'6", 370ish) carries his Glock 19 in a leather IWB every day, with no problems. Trouble is, he can't remember where the holster came from, and there are no markings on it. He says it was custom made, where the maker actually called him, and got all sorts of dimensions from him before it was made.
Keep us posted, and good luck!