It really depends on where you bury the body. Once you get out of developed areas, it gets very hard to track things down. Take this example; she was missing for two years, and her body was found in a tent, in a sleeping bag, just two miles off the Appalachian trail, which is one of the busiest hiking trails in the US. If someone was actually buried out there, the odds that they'd ever be found are very, very poor.

Admittedly, carrying a body off trails through fairly dense forests ain't gonna be easy. If you were going to do it, I'd say start by getting an old car with no GPS, get some paper maps, make sure that you leave all of your electronics at home so that there's no electronic trail of where you've been (especially your cell phone!), and only use cash for gas, etc. while you're driving to your body dump site. Assuming that the body isn't recovered for at least a year, you're likely in the clear.