So for our single byte of data, use sprintf() to convert to a null-terminated (thus 3 element) char array and then serial.print() that?
Yes. Only two bytes will actually get transmitted.
On the other hand, you could use Serial.write() and skip the whole conversion process.
Or, you could send all the data as strings, with delimiters, and it wouldn't matter how long the string is. "123!" or "1!" or "122864662!".