Just to close the loop, using a few RS232 Shifters (SparkFun PRT-00449) and the Netduino Plus 1, I was able to communicate at 19200 7E2. Unfortunately, after all of this, the barcode scanner doesn't support the UCCEAN128 barcode format required for the DHL label we needed to use. After all of that, the project was scrapped.
The good news is that we have identified a few other places on our manufacturing floor where the Netduino platform can be used,