Although I understand the appeal of what you're thinking about, I don't believe you can justify it economically. It's a lifestyle choice, and you certainly might be able to justify it that way.
You probably can't just park somewhere and set up a road show. Most companies I know of that do this have partners/resellers around the country and use their business property to park on and do shows. If you don't have that type of facility available, you're going to have to rent space, and possibly deal with local business regulations/permits, which can be complicated. I don't know the issues of commercial use in terms of DOT regulations, but you'd definitely have to investigate that.
Regarding deducting on taxes, you'll only have partial deductions based on the percentage of use for personal vs. business, just as with any business vehicle.
The trade shows I'm familiar with are mostly in larger cities, and most exhibitors stay at conference center hotels - partly because that's where most of their customers (non-local customers, that is) stay, and partly because there's a huge difference between taking a 2 minute elevator ride to and from work every morning vs. commuting to and from an unfamiliar city from rv-park distance.
Paul
