Note: I hope nobody is offended by anything I write here. I'm relating my own (limited) experiences from my own perspective. Take what I say with a grain of salt, as I am (very) white, but I may be able to offer a little insight despite my ethnic heritage, as I married an Asian woman (Thai), I have become quite close with her extended family, and have spent a bit of time there (and have traveled a fair bit around other parts of Asia). We have discussed race extensively (usually in the context of whites and Asians, but also how Asians view foreigners of African heritage - and also race as an issue in the USA) and I think they have been pretty honest with me about such things. I have been shocked, disgusted, pleasantly surprised, and occasionally charmed by various things I've heard my Asian relatives say about different ethnicities.
I think both of your characterizations are spot-on: yes, they are racist and xenophobic (sometimes shockingly so), like people anywhere can be - and sometimes its really open (I've heard things said by my Thai relatives that I can not imagine any American would say, outside of a Klan rally - they seem oblivious to the insensitivity...or maybe they just have not learned the acceptable way to discuss things). Other times they are perfectly OK and very cool, too. So you can probably expect both ends of the spectrum, and everything in between.
I think in most places you probably will not encounter overt, explicit racism and hostility. But you may get a few "looks", different expectations and, sadly, at times you may encounter a little less warm welcome than is normally extended to other foreigners. It seems that skin color is often a big deal among Asian people (a social issue there as elsewhere). If you stick to places that get a lot of tourists, you are not going to shock anyone, and I'd expect you to be treated as a valued customer (your money is the same color as everyone else's). If you get well off the tourist circuit, then you may get more unfiltered reactions.
More than being perceived as "black", I think you will simply be perceived as "foreign". After that, other distinctions may be secondary at best. Despite all our own struggles with race, at least here (in the USA) I think it's pretty common to encounter people of many ethnicities on a regular basis (at least in most places). In many places in Asia, I think things are a lot more ethnically homogenous - we "foreigners" just stand out more. In my experience, being viewed as a "foreigner" (and I think you should expect to be - I always am) has both advantages and disadvantages. Foreigners are often thought to be kind of clueless, so they will cut you a lot of slack - you will be held to a different standards (usually lower standards) for most behaviors. Visitors should still make a little effort to learn a few polite phrases and a few customs (lots of rules around respect, status, etc.). If you make even a small effort, they will probably think it cute and you will score points. Of course, the same is true whether one is going to Paris or Phnom Penh - a little politeness goes a long way. Regardless of your ethnicity, if you treat others with plenty of respect, it'll be hard for them not to return at least some of that. One can't generalize too much, but in my experience it's a very polite part of the world, what we call "politeness" is a major consideration in social interactions. Lots of amazing things to see and do, so well worth the effort.
I hope some of the above is useful and my apologies if I have stepped across any lines. Have fun!