Bed ridden father can’t pull his own covers on and off when he gets hot or cold. Is there a solution to this?

My understanding (from an Uncle) is that the drugs for prostate problems give a hot flush/ cold symptom very much like the menopause in women. My Uncle was a practical bloke who lived alone, and had rigged up a system of cords running through hooks screwed into the foot of the bed, then attached to the blankets so that he could pull on the cords with his hands at the top and shift the blankets over him and then off him. Another option could be for one of those newer electric blankets that goes over the sleeper, not under him, with an on/off switch workable with this hands. Take the bell away so that he has to make the effort to make it work.

Right now taking the bell away is not an option. His bed is at the far end of the house and mom stays in the living room up front. . He’s voice is no longer loud enuf fo hear if he had fo call her for something... I told mom that she needs to let him pull his own covers on and off. He can still use his arms and hands .... that the covers need to stay on his legs that they are always ice cold and thin due to poor circulation from a bad failing heart ... we td mom that she is just enabling him to keep exerting his control over her due to his anxiety... that she needs fo advise him the next time he rings that bell that is should only be used in an emergency such as when or if his uroscopy bad leaks or if he is hungry or thirsty only....that his being hot or cold repeatedly is all in his head and then he will quit that behavior ... she is definitely aggravated with him but she is the one who has to change it....

I read of a trick that some overnight hikers have been using. They don't want to carry a sleeping back because it may be too heavy and only has one layer of cover.
They use wide blankets and sleep on top of it and pull the sides over themselves providing them with layers to be removed or added as needed. One flap or side on the left and one on the right. That will give them two layers of cover if needed and can be reduced to one layer if two layers are too much.
If you want to try this check your thrift stores for an acceptable blanket.