How practical is it to backpack from Bali to mainland SE Asian countries?

I’m looking at booking a trip to Bali, and I would really love to just backpack up through Southeast Asia. I only have about two weeks to do so. It seems like a good path would take this order: Bali – Singapore – Kuala Lumpur – Bangkok – Yangon – Laos – Vietnam – Cambodia. If I happen to catch somewhere in southern China, I wouldn’t complain either. While it all sounds nice in theory, I’m actually quite unfamiliar with the entire area. I’m not even sure if it’s practical to cover that much area “on foot” in two weeks. Also, I’m open to all suggestions when it comes to travel in the areas mentioned; safety, recommendations, anything, really.

One last thing, if someone could brief me on crossing borders while on foot, that would also be greatly appreciated.

Thanks in advance!