Ember Simple Auth set session.data.token after authenticate

I am using ember-cli-simple-auth-token which works for initial login auth but not subsequent API requests. To resolve I am working towards setting the token after authenticate and adding the token in RESTAdapter as below.

Token:

{"token":"12345abc"}

Application Adapter:

export default DS.RESTAdapter.extend({
    session: Ember.inject.service('session'),
    host: 'http://127.0.0.1:8000',
    headers: Ember.computed('session.data.token', function() {
        var session = this.get('session');
        return {
          Authorization: "Token " + session.get("data.token")
        };
    })  
});

Authenticate looks like this so far:

authenticate() {

    var credentials = this.getProperties('identification', 'password');
    var authenticator = 'simple-auth-authenticator:token';

    return this.get('session').authenticate(authenticator, credentials).then(() => {
        var userToken = '4c00b675868eb53c605cb64281b356ace8795c5b'; // TO DO
        this.get('session').set('data.token', userToken);
        this.transitionToRoute('dashboard');
    }, () => {
        return true;
    });

},      

Any ideas on how I can set the userToken var from the response/promise value or alternatives to achieve this?