It should also be mentioned that most of the proteins aren't stable in hot environments from 70-80 degrees Celsius from what I remember. That means that thorough cooking should get rid off any possible venom residue. Proteins are also destroyed by things like alcohol. I wouldn't even be scared of those snake liqueurs from Japan. If they are properly made, of course.Idk about any hard and fast rules, but as long as the head is removed (where the venom glands reside) you should be good to go. So far the rattlesnakes I've eaten haven't caused me any problems after getting a French neck tie.
For what it's worth, most snake venous are derived from proteins the snakes produce in their glands. That means that, generally speaking, snake venom is harmless if swallowed. It needs to enter the blood stream to cause trouble, but it will have no effect if you swallow and digest it completely. BUT, if you happen to have any cuts, scratches, sores or ulcers in your mouth/throat/stomach then the venom can enter your blood stream and get to work. So, don't eat a bunch of tortilla chips before taking a shot. Otherwise, they have clean meat which is distinctly reptilian but not off-putting.
I wonder how someone hunts for rattlesnake?