As the weather cools off, if cold is playing a role, you can also try placing HotHands hand warmers, single-use air-activated heat packs, under the hand to try to relax the muscles in between massages; they can be used with or without splints. For those whose legs or feet get cold/cramp, I recommend trying Vaso-Wraps under clothing. Depending on size, they can be used on arms as well.
Of course, there are many kinds of hand (we used fleece "polar fleece unisex hand protectors" from Buck and Buck and it would be easy to insert a hand warmer in the palm or on top/side of the hand of one of those, or alternate), arm, and leg protectors, as well as traditional leggings.
Here is our
PT show 'n' tell for massage and ROM in a wheelchair. In winter, those are all the more important.