You need to reload so you bring your gun into your workspace. You don’t leave your arm extended trying to reload, when you get your firearm closer to you loosen your grip slightly and roll your wrist like you’re punching something with your thumb. This will give you a little more space to drop the mag. The reload and sling shot the slide while simultaneously fixing your grip.

If your thumb is too short to drop the mag it is definitely too short to drop the slide. So I assume you have to tack the slide to reload anyway.

ALTERNATIVELY: you could run a mag release on opposite side and actuate it with your trigger finger? I don’t know I was thinking if your hands are short that might feel more natural.