I used to run my 1700KV T8 in my Tuggy on 6S all the time. It was usless as a racer but it would jump anything and did backflips on command. But the motor took it just fine. 5S is going to be a handful in a buggy with a 1900. It will not be user friendly on dirt. And dialing it back usually creates heat in the ESC, so its not an optimal setup...

If you get a 1700kv motor 5S would be ok