Right. A bonfire, even when you use gasoline, just doesn't do the trick. Gets tried a lot though:
http://www.sfexaminer.com/local/ap/parents-of-wanted-socal-teen-arrested-79696777.html
http://www.wrex.com/Global/story.asp?S=13407422
The guy with the group that found the tarp and trashbags said on FB it was by a highway (the French-sounding one) up in the treeline.
In any case these were found by volunteer searchers per reports and they weren't searching inside Tina's house.
I guess we'll see. But it's not always easy to find a body on farmland. Morgan Harrington's body was placed on farmland and she was missing for quite a spell.