Digging would not look suspicious in a rural area. I'm guessing that they were inexperienced at body disposal (aren't we all) and tried the burning and dismembering to make a smaller hole - less work and more consistent with the raccoon story. I've buried my share of pets and even in the hard Arizona soil digging a hole put a medium sized dog in with a foot or so of dirt on top only took me less than 15 minutes. We've heard the soil in that part of Idaho is hard to dig in because it is rocky. That makes sense since I think the area is a glacial moraine. But I did not see a lot of rocks in the search pictures so it may very widely depending on specific area.
Not to get too gross here but people are animals. Most of us have experience cooking meat. On a hot fire you can pretty much turn a steak into charcoal in half an hour. I can see 2.5 hours being a reasonable time with some missteps. One digger, one griller...
I'm actually thinking that AC's possible trip to St. Anthony might have been to buy a pickaxe, saw, or axe to hasten the process. The man had a date with a taco so he was probably in a hurry. It could have been a stray ping as well. Maybe someone local can tell us if there is a hardware, garden supply, or similar store in St. Anthony.
