If anyone is still looking at this, here is my solution/workaround...
Issue: if using GV on Android some apps e.g. phone and others, except GV app (and possibly except hangouts works, but I dont like it), will send SMS with your carrier caller # and not your GV #, because GV cannot be set to the default sms app. the way to fix this is...
NOTE: the following assumes you never want your carrier # to show for sms and that you only want your GV # to show
1) delete any sms aps: settings -> apps ->(pick the app)-> uninstall
2) disable hangouts: settings -> apps ->Hangouts-> disable
3) make an sms from contacts or 3rd party dialer etc (I use exDialer)
4) you get a choice to send sms via GV and possibly other choices such as Skype. Select GV, and select always
Note: if you have any other SMS apps e.g. messenger, messaging, etc THESE MUST BE UNINSTALLED, otherwise after 1st use, sms will revert back to these.
5) from now on, sms will be sent via GV # (because there are no other installed options to override GV for SMS). (again is there are other options, Android will revert to those soon)
Note: I find the native Phone app, thinks there is no sms available so no option to send sms from phone app. As stated above I use exDialer for many reasons and that gives option for sms or call. If done as stated above sms will be via gv#, not carrier #.
(Side Note: the main reason I use exdialer is to be able to search like on iOS, meaning a few letters of 1st or last name, then a few of the other and/or few letters of any note/address or other criteria. This is in contrast to most Android phone/contact searches, which are far less flexible. that is an aside from the topic at hand, but others may want to know)
The result of the above is to maintain all sms via GV # and stay out of hangouts.