It can be done. It's true that Angkor Wat does see hundreds of thousands of visitors a year, and who knows how many on any given day. That being said, I was told that this ancient temple would be teeming with tourists and groups and guides and locals, and that I would be hard-pressed to experience any solitude. Well that is simply not the case. Two factors helped to alleviate this worry. First, go during the off season, which in my case happened to be in July, when fewer people choose to visit. And two, get up and go extra early, because while everyone says they will do that, you will find it's far fewer that actually go through with it. The experience of wandering through ancient ruins, with total silence save for a clicking camera shutter, is something that all travelers should strive to achieve whenever possible.