I have kept things simple and am using a third party app called Success Engine.
It allows a templated approach to integrate with Twilio and gives you the HTTP to add to any campaign (they do the backend work, which keeps the focus on the processes you are implementing).
I have added a number of texting campaigns and they have all tested and run successfully.
You can create unlimited campaigns with one number and Twilio via this app.
And you can get a discount on your Twilio number via Success Engine too, I believe.
(I am not an affiliate).
(Other things you can do with Success Engine
Success Engine is like “Plus This” but cheaper and you can get good deals with them.
It has saved me tons of time and allowed our campaigns to be quite robust adding up to 20 different processes to your campaigns and site.
We run all our custom fields and MATH to calculate next bill date to send reminder emails for our subscription, for example.)