Bryan, correct me if I'm wrong:
1. I would bring the recording levels shown on CEP as close to zero as posible.
2. I would do this by adjusting the "input volume" on the back of the UA-5.
3. While doing this it wouldn't matter at all that the peak light on the UA-5 stayed lit.
That's correct. The CEP meters will reflect the true, digital peak level. The "peak" light on the UA-5 is triggered at -2dB or some such, with some minor variance from unit to unit. Disregard it since you're able to use the CEP levels.
If you need to adjust L/R balance with the UA-5, try running into the front XLRs instead and using the front SENS knobs instead of the rear RCA inputs and Input Volume knob. It may work, or it may overload the inputs. If the latter, you'll know quickly and easily by giving the recording a listen - it'll sound distorted.