I'm thinking of dusting off this piece but could never find a solution which I was happy with for bar 7. Any suggestions?

Hmmm,havent played this one myself , but have a score in front of me. Is it possible to take the 2nd 3rd 4th 5th quavers in the alto part with the left hand ?

And hopping the 5th finger for the bass? Yes, that may be a possibility. I'm still struggling to find a solution for beat 2 - octave d in the left, trill in the right? - how to play the alto c the quaver after?

If you take the alto A,B,C D with the left hand, the B trill should be manageable with the right hand, then start alto part with right hand again with the middle C.. yes - left hand little finger will have to hop F E D.

I usually play this on 2 manuals with pedal (Bach has written the instruction "for 2 manuals & pedal"); the left hand uses a 16 ft registration, played detached, so you would need to play the other two parts with the right hand - again detached grouping the quavers into minim beats.

Yes, I've heard it played like that - does that mean taking a 4/5 trill in the right hand?

Did Bach specify 2 manuals and pedal? In my edition (Novello), it only says 'Man. Princip.8.F.' and 'Ped. Tromp.8.f'.

Yes, 4/5 trill, but a short one (4 notes with the alto D) - I have "2 manuals and pedal" pencilled in on my edition (Breitkopf) but can't remember the exact source for it - possibly original manuscript? but the instruction is found in Hermann Keller's "The Organ Works of Bach".