The short answer is No, there isn't an app that will use your GV# over your phone's actual number.
I'm not sure what Google has done to accomplish this but in every instance I know of the GV# is rejected.
You will also find that GV is very restrictive when it comes to messaging. In a recent discussion I actually uncovered a lot of information about GV and messaging. Some of those highlights, or not so highlights, are;
Group messages are limited to 7 contacts.
Resending the same message or sending multiple messages that don't get replies will result in your account being suspended and/or removed.
Sending too many links is subject to suspension and/or cancelation of your account.
And the biggest of them all, Google doesn't care. Teacher's, churches and not for profit orgs. were asking for such privileges and Google flat told them, find another way.
Here is the link to that discussion...
https://forums.androidcentral.com/a...nd-google-voice-group-mms-limit-new-post.html
You're probably better off using something like Tango or one of the other hundred or so apps that offer messaging with an alternate Phone# included.