Send file using wifi to my MacBook while connected to wi-fi
In my suggestion, instead of finding one virtual interface why not you add option in your script itself to associate with Transcend before transfer and when its done it comes back to your original network.

To do this, you just add below given commands to your script. 


Whenever script finds a new file, it force to associate the Transcend's    SSID (I assume your Mac is already associated to Venue's Wi-Fi)

networksetup -setairportnetwork en0 Transcend_SSID PASSWORD
This command will force to associate with Transcend's SSID.
Check the association

networksetup -getairportnetwork en0
Once Transfer is done remove the Transcend SSID from the network and toggle the Wi-Fi power.

networksetup -removepreferredwirelessnetwork en0 Transcend_SSID

networksetup -setairportpower en0 off

networksetup -setairportpower en0 on
According to Wi-Fi property it will associate back to your venue's Wi-Fi.


I think it might be helpful to you. It will break your connectivity with Venue's Wi-Fi for very less time as script is always running in background. Please let me know your thoughts.