You can have a single story a (to mimic handwriting) which is also distinct from other forms like the d and the o. Andika does this nicely:
There is an alternative a (on the right) as an “Literacy alternative”, as in long-form reading. As a data-point: Andika supports IPA, the a and the Latin alpha look the same.
There is also the IPPH language for the Latin script for use with the IPA, maybe that could trigger the a to assume the two-story form.