Actually your Presonus interface might work quite well for your purpose. Just enable the Combine USB & Headphone Outputs option. Then you can route the main output to the Presonus and the Aux to the headphones. That would be the cheapest option for your. An even smaller footprint would be to use the lightning headphone adapter as one output and the iPad headphone socket as another.
I do get the click request now and then but the problem I see is that without a proper beatgrid it is not possible to fit a clicktrack to the playback. Most playbacks don't start right away with the downbeat. So just playing a click with a certain tempo will most certainly be off from the start. Even if you add a delay at the beginning, it would run out of sync quickly on slight speed variations.
But, I have looping functionality planned in 2022 and that also requires a good beatgrid implementation. So once that works, adding a click will be quite easy.