The best compromise i can currently come up with is to go trekking somewhere very cold and high on a conventional 'holiday', to a place where you can perhaps access critical drugs more easily than here, ideally morphine ie the himalayas or argentina.. Freeze to death up there and or die from high altitude sickness at 5000 metres while making it as comfortable as possible. Make sure your drugs are repackaged into things that won't be found and indicate suicide, like a trekking water bottle. The shit is going to hit the fan whatever happens for dealing with the death for family, but at least they might not have the long term repercussions of suicide, rather that you died doing something you loved..perhaps. An autopsy may well find high levels of drugs in your body but it depends maybe on how long it is before you are discovered. There are no easy answers to this if you wants to try to protect yourself from the pain of life and others from the pain of your death, especially a messy one.
I think if someone in my family ctbd by hanging or CO and especially something very messy, it would haunt me much more than if they died with at least some uncertainty about it, even if i suspected something but could somehow understand what might have happened and the circumstances involved.