Bill, have you ever found Mauka to hybridize with any of the wild four o’clocks such as Mirabilis nyctaginea?
The sweet yellow root of Nyctaginea was supposed to be used for babies cough and given to women after pregnancy to reduce swelling according to Wikipedia. Looks like Nyctaginea has a native range in Washington state.
I have tried M. jalapa without success, but that’s it (and no success, although I only made about a dozen crosses). It should be possible to get Mirabilis species to flower simultaneously in a greenhouse. I haven’t found much information available about chromosome number in Mirabilis, so it is hard to predict what might work, but I think any cross is worth a try.