In reply to Charcot Marie tooth:
I'm familiar with the problem. I've worn 7+ insulating layers and still been shivering on my scooter. Although I haven't tried one myself (friends have praised), heated jackets might offer some solution for us.
One thing I've found, which I guess is quite obvious, is that slowing down, as frustrating as that may be, will make a big difference. Sometimes I just have to act like a lizard and find a sheltered sunny spot and angle myself towards the sun until I'm warm enough to move again
Jamming a handwarmer into a glove helps. Not sure about wheelchair, but on scooter your arms and hands are quite exposed on the handlebars so I wondered if some of those handlebar type gloves used by kayakers and cycle couriers (are they called pogies maybe?) could be useful.
Sorry, that was just general advice rather than an answer to your question.