In no particular order:
Dry shampoo is a real thing and you can use it every day, supplemented with a damp cloth / brush/comb to get the scalp clean. I just used it for my dad's last weeks. I basically combined the shampoo and rubbing with a damp cloth and then combed through. I know, you have long hair but the concept is the same.
You could also potentially use some kind of hair wand system in a chair or bed, with lots of towels.
I was not arguing for a shower bay at all given your home setup.
Hypoallergenic cleansing wipes for those nether parts do work pretty well. My husband relied on them for some years.
Jimi's wash cloth is another option.
By the end of our ShowerBuddy year, my husband was cold and exhausted after every shower. It was good while it lasted but he was ready to give it up.
We always have to prioritize what "current state" we are going to work the hardest to keep for the longest time, because there is only so much time, energy, and money. Maybe for you, that is a shower. That was not the case for us.
If you want to spend your last days somewhere else than where you are now, go for it, but start planning so you know where that somewhere is, and can discuss/plan with your family. Later on, they will probably be more in block and tackle mode, so the time to plan for later is now.