This is going to be a partial post that I'll get back to later because the subject is incredibly complicated. I've taken very few travel related write-offs over the years as an author, primarily transportation expenses to and from industry shows and events, a few hotel nights, some meals. However, I'm considering a three month trip overseas this winter for the purpose of travel writing, which I hoping will be fully deductible. I decided I better start doing my homework early, which led me to Publication 463 from which all of the quotes in this post are taken.
To be traveling away from home, you need to have a home. For a sole proprietor, your tax home is your main place of business. If you're a travel bum, you're in trouble because you may be defined as a "transient." Transients cannot claim travel expenses, period. However, you may be able to use the home where you regularly live as your tax home, even if you have no main place of business or work. The IRS has a list of three factors used to determine your tax home if you have no main place of work. Match all three, you're gold. Two out of three is a maybe. One out of three and you may as well be a transient.
The IRS also differentiates between temporary vs. indefinite assignments. "An assignment or job in a single location is considered indefinite if it is realistically expected to last for more than one year, whether or not it actually lasts more than one year." Not surprisingly, if your trip is "indefinite" you can't deduct travel expenses.
When it comes to meals, you're expected to live somewhat normally. "You cannot deduct expenses for meals that are lavish or extravagant. An expense is not considered lavish or extravagant if it is reasonable based on the facts and circumstances. Expenses will not be disallowed merely because they are more than a fixed dollar amount or take place at deluxe restaurants, hotels, nightclubs, or resorts." Somehow, I read that paragraph and I still don't know what "lavish or extravagant" means. In any case, you can only deduct 50% of meal expenses. On the whole, I'd rather do a per diem if possible.