One can not hide, but can get unlimited Gmail accounts ie. spoof20123@gmail, spoof20124@gmail....
Next get a dirt cheap gsm phone ie. BLU green/red $10.00 from NewEgg
Next get free sim card(s) from a dirt cheap gsm carrier ie. Lycamobile $0.02/min
Now link your spoof20123@gmail with that sim card.
Login to your OBI-whatever and change GV username to spoof20123 when you want to spoof
Change it back when you don't want to spoof
When you are tired of that spoof GV number, just either remove it and get a new one or use another spoof20124@gmail(a new GV number) to link your LycaMobile number.
I still have some GV numbers link to PagePlus numbers I used to have.
Unless Google starts to ask users to renew the link timely, those numbers will be there forever.