Ipad Mini 4 not giving the "send as SMS" option in messaging

Hello jcarta,
I understand that you would like to use SMS messaging on your iPad Mini. The answer to that is going to be no. The reason for that is because it is using a feature called Continuity.

One of the features of Continuity is that it will take the SMS text messages that you have received on your iPhone from someone that doesn't have an iPhone and forwards them to your iPad. So the requirement is that you need to have an iPhone and an iPad to get SMS messages to show on your iPad. The iPad itself can't send SMS text messages without an iPhone. For more details, take a look at the article below.
Use Continuity to connect your iPhone, iPad, iPod touch, and Mac
https://support.apple.com/en-us/HT204681

SMS

With Continuity, all the SMS and MMS text messages you send and receive on your iPhone also appear on your Mac, iPad, and iPod touch. Even if the person you’re communicating with doesn’t have an iPhone. And regardless of what phone they have, you can reply from whichever device is closest to you, including your iPad or Mac. You can also initiate a conversation by clicking a phone number in Safari, Contacts, or Calendar.

To use Continuity for SMS and MMS with your iPhone and your Mac, iPad or iPod touch

Your iPhone, iPad, and iPod touch need to use iOS 8.1, and your Mac needs to use OS X Yosemite.

1. Sign in to iMessage on your iPhone, your other iOS devices, and your Mac using the same Apple ID.
2. On your iPhone: Go to Settings > Messages > Send & Receive > You Can Be Reached By, and add a check to both your phone number and email address. Then, go to Settings > Messages > Text Message Forwarding, and enable the device(s) you would like to forward messages to.
3. Your Mac, iPad, or iPod touch will display a code. Enter this code on your iPhone to verify the SMS feature.

Take care

An iPad is a data only device, but SMS text messages are actually carried in a cellular telephone voice channel. Since the iPad does not have the ability to make a voice channel connection it cannot natively send SMS. As mentioned though, if you have an iPhone you can use Apple's continuity feature. With continuity, the iPhone actually does the sending and receiving of the SMS texts and shares them with the iPad over wifi.

Hey jcarta,
Glad that we could clear this up for you.
Have a good day.