You can store the letter 'ŭ' by its letter name "ŭo"; it's letter name is different from the letter name of u, which is "u"

so you can just store each esperanto letter by its name to perfectly encode an esperanto sentence (including the ŭ letter).

example: [a uo u lo o] is translatable to and from [a ŭ u l o] because of the differences in letter name.

so any other system than the h-system is not needed at all.