Should I try to walk out of the wilderness if I'm bitten by a poisonous snake?

That depends on how long it will take to get to the hospital. Remember that first-aid, mostly in the form of suction, does very little for a snake bite. The best treatment is anti-venom which is usually only found in an emergency room. If you can NOT walk calmly and easily to a car or ambulance within a few minutes, seriously consider arranging for a helicopter to transport you to a hospital. They are quite affordable compared to the value of your life.

An alternative to a helicopter is a litter evacuation. This is often a good choice for a long hike out and when there are enough people around to carry the make-shift litter and no outside communication can be established.

Don't forget to take a cell phone when hiking (unless you are carrying and emergency room in your pocket). The direct numbers to several helicopter companies with qualified mountain pilots are also helpful.