if you have a levitating top you can look at the aerodynamic side by itself.
A Levitron in the vacuum doesn't spin for long, there is a magnetic drag.
It doesn't seem to me a so good way to measure the air drag of a spinning top.
It seems complicate, also.
It is a matter of taste really what is legit.
"Legit" doesn't sound a correct term here, if there are not rules to obey. You can say "I like traditional tops", "I dislike new ideas", ok... a matter of taste in any case, as you say.
As for spin time records, would a Simonelli under a shroud be legit? Bet you could get well beyond an hour that way.
I don't know, it would be not up to me to decide. But I am not looking for a new official record, and I will not do it.
I am just trying to make something different; it can become boring to make things always in the same way.
I think I can reach maybe 65 minutes with a shroud, not much more, because my best tops have already low air drag by themselves.