I am not certain that the liquid extracted from brown rice for rice milk should be a problem since it doesn't contain the bran which gets filtered out during packaging. Brown rice flour on the other hand will contain bran. Over the years I have experimented with small amounts of bran and found that even the smallest amount causes problems.
Don't let SIBO spin your head too much Over the past couple of years it has been clearly demonstrated that the lactulose breath test that has been conventionally used to determine the presence of SIBO is invalid. It potential role in IBS now appears to be quite limited. If you decide to get tested for SIBO make sure they use a glucose breath test instead of a lactulose breath test.
-------------------- STABLE: ♂, IBS-D 50+ years - Science of IBS