WELL. This has been an experience. I've said it before and I'll say it again: I'm not a strong programmer. Taking a Mouse/Keyboard input combo and translating that to dual virtual joysticks has easily been one of the more headache-inducing experiences of the last few months. This was aggravated by the fact that the Unity Remote app apparently hasn't been updated for 100% compatibility with the new GUI system. My joysticks worked individually, but not together. I wasted a full day (at least) browsing forums and messing with my code before I learned that it was a limitation of the app, and not my code. Once I was over that hurdle, it was a fairly simple process of rebuilding my weapons, and weapon switching mechanics. One nuisance I still haven't resolved is shadows. I do not have shadows on my mobile build and I have no idea why. I'm trying not to stress about it, but it's driving me up a wall.

UPDATE: learned a very valuable lesson about Unity's Quality Settings. Things make a lot more sense now.