In a shocking twist, redoing the remapping controls menu has actually gone very smoothly! Here is a brand new menu that can be accessed from the main menu AND pause screen. You can see the keyboard/mouse and gamepad buttons assigned to your actions and map each one. There's also convenient "Set all" and "Reset to Default" actions that do exactly as you'd expect.
Input supports a lot of controllers I couldn't before, so drawing up the icons for each button has been tedious (and the reason this has been taking a while), but luckily the Super Freaks community has been helping me draw some up to speed things along. Thanks everyone!
1