Songbook App - transposing for guitar and capo

I want to use the Songbook app on my iPad to display guitar scores for performance. I'll often have scores in a particular key, but need to transpose them on the fly when performing. The app includes a transpose function which is great, but a little limited for my needs. What I tend to want is:

1. Song is in C, but we want to drop it a semitone, to B, for example.
2. But playing in B is a pain, so I then want to capo it to the 3rd fret and play in G.

So there's two separate adjustments I want to make, drop a semitone in actual pitch, but then add capo to choose the chords to play without changing pitch. Doing those calculations in my head so I can set the transpose slider to "G" is fiddly, and worse still, there's nothing on the score to remind me to play capo 3. I'd also want to save the two settings along with the score, so I can set things up at the start of the session, and not have to fiddle just before I play the song.

Is there any facility in the songbook app to do something like this? Or if not is there any other iPad app that reads MuseScore (or MusicXML) files and does have that capability?

Thanks,
Paul