Snake will kill you sure, but its gonna hurt like a devil. No pain killer other than straight up morphine is going to take the edge off it. But it will work. If you want it to not look like a suicide, drink a bit, drain your phone battery, put on headphones hooked up to some non phone device so as to not be suspicious about why you are wearing headphones. Headphones and drink would keep you from noticing the snake. Go on a weekday mid day. Any other time, you are likely to get caught. Make a habit of going and just hiking so it's not unusual behavior. Use this time to learn to find them. They are hard to spot. I've only come across one once and it was an accident. I never saw him, just heard him.
This is quite extensive to not look like suicide. Get drunk for reals and breathe water. That'll do it. Again though, make sure you can't get found. Becoming a vegetable or severely mentally handicapped and not having yourself as a way out would really sucked.
Don't do any of these things:
https://www.wikihow.com/Avoid-a-Rattlesnake-Attack
or these things:
https://www.wikihow.com/Treat-a-Snake-Bite
and do learn things from here to help:
https://www.trails.com/how_2197_identify-rattle-snake.html
This timeline on this page is alarming.
https://www.healthline.com/health/rattlesnake-bite#timeline
It may take days to finally die. The wikipedia article mentions some people that go within minutes from a bite. Some were hours. Theoretical days though? Not my cup of tea.
There is also the chance that whatever rattlesnake you do find is already spent or not willing to spend it on you. Adult snakes can control how much venom they let go. They may give a warning nibble with none if they are hungry and going to look for food later. They may inject none if they ate recently and used it there. They do not have a limitless supply.
Overall it is not a reliable death really and it may result in long suffering even if the end goal is met.