Bach Cantata 170

[innate]

I am due to play the organ part of this cantata in a few weeks time. The plan is to use a standard 3-stop continuo organ, as the conductor thinks the obbligato organ part is playable on one manual. I've just received the part and, whilst that would be possible in a Goldbergs-on-the-piano fashion, I'd rather have a more practical and perhaps more musical solution. It might be possible to play the left-hand part down an octave; using 4' or 4'+2' might work! Alternatively an organ with split stops, or two organs (!) might be feasible. Of course the obvious solution is to use a two-manual instrument but that might be difficult for financial and practical reasons. If anyone has experience of this piece I would be glad of any advice. Thanks in advance.