Have you tried swapping grips on the P226 or adding a Legion/P224 slide lock? I found the E2 grips pushed my hand lower on the grip and I didn't ride the slide lock anymore. I didn't care for them in the long run, switched to G10 and installed a Legion slide lock. No more issues.
JMCK makes holsters for this combination. It's a PX4 FS holster, so you'll have a little more material around the muzzle.
If this gun were for defensive use, concerns over not going to slide lock would be pretty far down the list for me. Having a gun that I can shoot to the fullest of my ability would matter more than not riding the slide lock lever or being able to press the mag release without shifting my hand around.
That being said, when I shot Sigs, I stopped having slide lock issues once I switched my grip around to where my dominant hand thumb would rest ontop of my support hand thumb. The P224 slide lock lever has a lower profile than the standard slide lock levers and they can be bought seperately and placed on other Sigs like the 226 and 229. Sig even puts them on all the Legion guns.
Quite sure this is his thread.
https://pistol-forum.com/showthread....(8)-Custom-Key