There's a skill called MailBox that reliably originates texts and emails to folks that you have put on a list, or replies to texts & emails from anyone. It links to your Google accounts, including Google Voice.
The list format for the text origination is interesting. You have to go into a received text, extract the full address string, and make that the detail for the person in question. It looks like
John 12015551212.18183456666.Qde1eYT@txt.voice.google.com
With the first phone# being the one you were assigned by google, the second being the recipient's phone#, and the remainder before the @ being necessary though unknown to me. So you can be prepping your meal in the kitchen, and say "Alexa, open Mailbox and send an SMS to John" and it will direct you on how to proceed.
It's pretty awesome. But again, you have to use a Google Voice account.