Hi there, @ggreenwood ...
I'll be honest...I'm not really sure what the "Template" check-box is for. I looked around the Commons Guides for more information on what that particular check-box means, but I can only find this: How do I edit the details of a resource in Commons... - Instructure Community (canvaslms.com). Look under the heading "Select Content Type", and you'll see the option for the "Template", but it really doesn't have a great description of what it actually does.
With all that being said, I don't really know that sharing your page to Commons and marking it as a "Template" has much value...though I could be wrong (wouldn't be the first time). I guess the question is...what is the end goal of the template? If you built pages using a template (let's call this the "parent"), would you ever update the template in the future and then want/need the "child" pages to update accordingly?
Another option would be to make a content page in your course labeled "template" in some way...then you could keep it hidden from students. Then, you would just make copies of that page to use throughout your course. However, if you wanted to update the "template" page, that wouldn't push out any updates to the "child" copies you made.
Let's keep brainstorming this so we can find a good solution for you. Hope to hear back from you soon.