I don't know why I didn't think about the clearance; that's a very good point. Does the low clearance affect maximum roughness and slope of the track as well?

[edit]

Did any of the hyperloop competitors try the addition of a skirt, similar to the UK's old hovertrain?

[edit2]

Googling for "hyperloop skirt" found this article: https://waset.org/publications/10004923/conceptional-design-... which suggests a 2cm clearance, but no clue if that's a reliable source.