Not only can you apply for it while you are in the US, it's arguably more convenient to do it that way. When the BOI endorses your application, you apply via eVisa (I believe LA is the designated consulate for Hawaii, not that this matters that much, except that you MUST use the correct one), and the visa is issued as a document you print out and carry with you to enter Thailand. You do not mail your passport anywhere, you do not collect a pile of documents and trudge off to an office in Bangkok, etc.
Assuming you have all your documents in order, the whole thing from start to finish can be done in under 6 weeks from the comfort of your home in Hawaii.