Definitely made some good progress in the prototype over the weekend. In addition to replacing the capsule I'd been testing with with the above mech model (Futch was right, placeholder art is WAAAAAAY better than using nothing but programmer art), I managed to break out the physics and transform controls from the script handling input, and implemented a basic physics engine to boot.
Right now the physics engine handles application of forces reasonably well, but collisions with anything other than axis-aligned planes doesn't seem to work. That is, flat walls and floors stop the mech no problem, but it cuts through sloped surfaces (mostly ceilings). I think this might have to do with fighting between the raycast checking for the floor and spherecast checking for collisions with walls. Maybe making it all one spherecast, or some sort of while loop checking for wall and ramp collisions would suffice?
I'm also thinking that I should move the physics code from Update() to FixedUpdate(). Even though I'm not using rigidbodies or any of the built-in physics code outside of raycasts, it'd be nice to have that level of consistency.