CAN busses have controlled slew rate to minimize external EMI. Examine those edges, at the 8 µs (125 kbaud) bit rate. I'd expect about 1 µs.
The round trip time for 60" will be 20 nanoseconds or less. I'd expect that 20 nanosecond to be invisible on the 1 µs ramp times. Hence the edge fidelity is high.
Your remaining bit error rate risk is the built-in hysteresis of the CAN receivers.
Check the CAN bus specifications, examine the maximum allowed hysteresis, and verify the signal-swing when loaded with the additional 120 ohm load will still produce a signal swing at least 50% higher than the maximum hysteresis.
This 50% margin is to ensure some noise immunity.
You could assist/improve the noise immunity by heavily loading the differential bus with 1,000 pF capacitors. 40 ohms and 1,000 pF capacitors is 40 nanosecond TAU, and the edge ramp will not change shape with 1,000 pF in parallel.
Just some ideas for you to try.