I think this would be certainly fine. Seeing as the rules only prohibit powered devices or vision-impeding things, a stepstool should be fine, as long as it isn't powered. Not that I can think of a way you could power it
.
Also, seeing as the GDC says ok (jokingly, but still) to baguettes and turkey legs, this should definetly be fine.
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2016 - NE District Championship Entrepreneurship Award
2016 - Hartford District Industrial Design Award
2016 - Waterbury District Engineering Inspiration Award