I have small hands and a similar issue, except with the mag release. I have to shift my hand to drop a mag, the slide stop/release is not a problem, though I use it only as a stop and rack the slide from the open position to chamber a round. I was going to install an extended mag release, but decided against it and worked on technique instead. I did this after talking with a few instructor's, that I have great respect for, and they said that I would end up needing to do it on all of my guns once I got used to it and if I ever had to use a gun that I was unfamiliar with I would end up adjusting my technique due to the lack of the extended release. It didn't take long and I'm able to do reload's plenty quick.
I own a G26 and other Glock's, so once I worked out my technique it transferred to my other pistol's, as well as, others that I've fired, including M&P'S, Ruger's and Springfield XD's. It's up to you though, I'm just presenting another point of view. Good luck.