@Sean Sands
You can create a brand and chose a low volume conversational campaign time for this use case.
Check this link: https://support.ringcentral.com/article-v2/Setting-up-TCR-registration-assigning-numbers-to-SMS-campaigns.html?brand=RingCentral&product=MVP&language=en_US
For opt in consent, yes it's needed even for 1-1 conversations, but it's not as strict as a marketing messaging consent. So for your case, as mentioned in above article, it may fit in
"Initiating the text message exchange in which the Message Sender replies to the Consumer only with responsive information."
You can provide details on who initiates the message and if it's your customer, then it's kind of implicit consent. If your office starts a SMS normally, then yes you need to document the consent of the recipient.
For sample messages, you just need to provide real examples that your business uses. "I am running late for a meeting", "Can we meet over lunch today?" are perfect examples. For conversational use cases, these kind of examples are ok.
Hope this helps.
Regards
Gurpreet Singh
GPM, RingCentral Inc.