There is a very high chance of voltage spikes/drops during ignition, and even when running the engine.
So, at least to use a timed relay, to switch on/off power to the RUT after certain time of stable onboard power/power loss
For a professional install, a (small) battery buffer (even better: UPS) takes care of stable power to the RUT, when engine running. And avoids power down of RUT because of short interruptions.
The RUT955 to be discontinued, soon.