Render a datetime as datepicker and text field

I would like to render a Datetime field as two different inputs: a datepicker and a text box where the user can input the time in their timezone as military time. I’m having trouble figuring out how to put both fields together to update the field when the model is saved. Any help would be greatly appreciated.

You might want to consider using two ui-only fields and create a model action triggered when the values change to run some javascript which would update your database field.
On query you would need to get the value from the field to fill in your ui-only fields.