Since you will lose a large portion of your benefit if you use Chapter 33 while only taking online classes, it may be in your best interest NOT to declare your classes with Veteran Services and instead use alternate financing such as seeking a Board of Governors (BOG) waiver instead.
One other wrinkle regarding online classes: the DVA will not pay for any remedial classes that are taken online. So in general, any math class with a number of 100 or less or English class of 114 or less won't be payable for benefits if taken online.
Effective 1 October 2011: You will be able to get BAH while taking only online classes - but at a much lower rate: half the national average BAH for an E-5. (The full-time rate for an individual eligible at the 100% eligibility tier would be $673.50 for 2011. Remember, BAH at this point will be prorated: so if you took only a half-time load using only online classes, you would only receive $336.75 in BAH each month.)