I thought about this method too. I was going to go to a country like on that show dark tourist where anyone can just go and do this. But doing the whole thing by myself would be a really intimidation mission.
Sorry, I'm sorry you're struggling but I don't think it's fair taking someone with you, even if you only kill yourself on a later solo visit, they'll find out and will not only feel used but develop a guilt complex.
My personal hope is that euthanasia will be available to me some how, some where, but it's probably me being optimistic, which is a rare thing for me. Suicide is beyond hard. But euthanasia would be a walk in the park in comparison.
Oh and btw I've never held a rifle before but from what I've seen, most are too long to be able to aim at yourself, unless your goal is to shoot yourself in the foot??