I don't know if if's still doable at this point, but an ending animation with Tav (romanced or not) going in his direction to try to find him would be enough.
Well, since they've changed Tav's facial expressions, because AA fans said 'it removes player agency', I think it's totally doable here too, especially because Tav isn't voiced and not being able to show your concern in this scene removes player agency just as well.
