My understanding is that medical science frequently declines the kind offer of people’s bodies. So then you’re back to square one.
Me and Mrs F made wills last month so this did come up. I opted for cremation on a whim and she left her options open. When the time comes I don’t gaff where my ashes go, on the compost heap would be fine. I remember a few years back when my granddad died my dad wanted to throw his ashes in the river in Norwich for some reason, so we all went down there on a chilly winter morning, but we didn’t do it because for some reason god knows. So bear that in mind: once your rellies have got over your death, then your funeral, they’d probably not appreciate having to jump through yet another hoop to toss your dust in the wind on some inaccessible hilltop.