"High-schooler" vs. "high schooler"

My initial attempt to settle the question with a google search didn't help as much as I'd hoped:

• A search for 'high schooler' revealed approximately 4% of results employing the hyphenated form.

• A search for 'middle schooler' revealed a significantly higher rate: 20% of entries employed the hyphenated form. (Including this recent article.)

• A search for 'elementary schooler' revealed no use of the hyphenated "elementary-schooler" within the first 100 entries. (I stopped looking after that.) So, effectively, less than 1%.

Based on this search, it would seem that "middle-schooler" is somewhat acceptable and "elementary-schooler" is not acceptable. "High-schooler", however, is unclear.

What I'm needing to decide right now regards the usage of "high-schooler" which I personally prefer to "high schooler". Even though google search trends suggest "high schooler" is used much more frequently, can I get away with using the hyphenated form as a stylistic choice?

My feeling is that if "middle-schooler" is allowed, then "high-schooler" should be just as permissible. After all, someday I might have to type something about a "high high schooler", and I'll wish I had been using the hyphenated form all along.

I ran an NGRAM of high schooler, high-schooler, highschooler, high school student, and high-school student.

Click here to see the results.

By far the preferred nomenclature was high school student. High schooler was a distant third, and high-schooler barely mapped. This result was surprising given the rule of hyphenating compound adjectives, but I guess that high school without a hyphen is a standard morphology.