Maybe complexed Salvinorin A dissolves differently in water. That may be a way to check, not sure (uncompleted Salvinorin A with simple HPBCD added may also increase water solubility).

Another option is to destroy HPBCD in a strong acid. Salvinorin A may precipitate from a water solution. Downside is that the precipitate may be something else if the acid is too strong and destroys everything or if there is no window where Salvinorin A survives while HPBCD is destroyed.

This is all theoretical, but could make for some fun experiments. Maybe there other better ideas.

Edit: it is possible that HPBCD (and complexed HPBCD+Salvinorin A) gets trapped by a water purification ion exchange resin, while Salvinorin A does not. That may open an interesting line of experiments.