I think using HH is a bit suspect to some people, you can try using numbers instead, so since H is the 8th letter of the alphabet you could use 88 instead.
Also you can add something to the beginning to identify you personally, like if you graduated in 2014 you could make it 1488.
That way nobody would get confused. :)
That’s literally the Nato name for the su-57, the Russian attempt to make a 5gen fighter.