Looking again at your question about traffic, scenery and good lodging, follow the Mekong. unless you need to have mountains. The east road sucks for travel because of traffic.

Oh, the traffic laws here are just suggestions. Do not stop at a stop sign, definitely stop at a red stop light and look carefully before proceeding thru a green light.
I have been traveling on a 2-lane road and have had 3 large trucks traveling abreast come at me multiple times. Alway keep an eye out for an escape route to one side or another while here in Cambodia.

Let me know if you come thru Kampong Cham and I would like to meet you and ride a bit. PM here or email bwilli88@ Gmail