Do you have access to a swimming pool at all? Is there one in your neighbourhood? I have started doing aqua jogging (in the deep pool with a big floatie around your waist) — you literally jog around in the water. I also have balance and proprioception issues – and it was recommended to me by Gareth Parry who is a CIDP/GBS specialist.
It is definitely cardio vascular! Another is Pilates — you can do it lying down! Some of the exercises I can’t do, but it has really helped to strengthen my core muscles which makes a big difference.
A couple of ideas, maybe?