If you don't have a latex allergy, then purchasing a mattress or foam topper that's
100% natural latex is one chemically safe option. Take care that it specifies "100% natural" and not simply "natural", as the latter can still contain a fairly significant amount of synthetic rubber, which is made of petrochemicals and real nasty stuff.
Since you find a tub full of water relaxing, I'm wondering if you might be interested in reading up on sleeping in an isolation (float) tank. It's just a couple inches of water super-saturated with epsom salts so that when you lie down in it your body floats completely, and the tank is generally built to be lightproof and soundproof to provide for relaxing sensory deprivation. It is said that a lot of people find them helpful to sleep in. Me, I've never tried it, but the idea of having literally no pressure points whatsoever as I'm lying down sounds like a dream!
I currently sleep without a mattress out of necessity. I have some boards that I sleep on with a blanket folded over that provides some cushioning, and the pressure points have built up calluses on the skin so hat it isn't as painful as it sounds anymore.
I've written fairly extensively on my own bedding journey in
this post. If you just want to skip to my suggestions then scroll down to the bolded part and read from there.
One thing I forgot to mention in that post is I've also experimented with sleeping on a cot (army surplus from something like 50 years ago, cotton, washed it and everything, still wasn't tolerable to me) and have also looked into sleeping on hammocks. You might be interested in the hammock option - contrary to popular belief you can sleep flat while in a hammock, and many with back problems actually find them therapeutic rather than damaging. You just need a hammock that accommodates lying on them at an angle.
The outgassing of new mattresses are a real worry. Does anyone have any recommendation for organic mattresses that will not cause that problem?
For those without my extreme sensitivities, any orgnaic mattresses ought to be okay. One that I can personally recommend is
http://holylamborganics.com/ , I haven't purchased any of their ready-made stuff but they're the ones I got my orgnaic wool batting from for my homemade mattress before I had to give it up. So I can attest their product is pure and their customer service is great, at least it was several years ago.
I have a hospital bed but got a different mattress. Because I spend so much time in bed, a hospital bed is ideal. It goes up and down, legs goes up and the upper torso part goes up and down. I have a bed rail on one side, which is really handy because you can pull yourself up. I have 2 beds. One in my bedroom and the other in the family room. My insurance paid for them.
A hospital bed sounds wonderful. Having the bed do the work in sitting up for you is really nice.
A final tip: when I've had my choice of height, I've found that beds raised higher than normal are easier to get onto an dout of than normal height of beds. If it's just below hip level I can sort of roll onto and off them, rather than having to bend my knees and use my leg muscles to get up and back down again. At one poitn I was actually sleeping on a desk because of this energy-saving convenience. Of course, experiment with what works for you.