"I'm sure if one were ever audited though, they'd have to jump through hoops to prove they lived aboard." No hoops requied, the IRS is up front about what is needed to make something into a "home", and that's typically a bed
, toilet, and kitchen (in plain language). Whether your home is tax deductible, a primary residence, a vacation
home, etc., depends on a whole host of other rules but the IRS has a very good web site with all of their publications on it. And, they'll mail you copies for free if you prefer.
Meet the published rules, and you'll sail through any examination or audit. No pun intended.