I would try the new PowerScan Standard Range made by Datalogic, it can write on a in-sight single RFID tag with the comand:

[DC2][ESC][w<EPC>[CR]

Or in case of a tag in a crowded environment (to target the right tag):

[DC2][ESC][w<EPC>;<TagID>[CR]

Be ware! the EPC is only supported in RAW format.