You can buy RVs pre-built on a bus chassis and they'd also have a bathroom along with whatever else you'd want.
I still am not sure why you want this rather than a limo. A chauffeured limo allows you to do some work while commuting, but is not as useful as a bus. However, a bus is a little less ideal for city travel and parking. A large van can allow you to have an office in less space than a bus, which might cut down on the commute time.
If the commute is very long, a helicopter would be superior, and people such as Trump tend to have a helicopter to cut commute time to a minimum, as in most situations a stationary office will be superior to a mobile one. In the context of South America, a helicopter also needs less security as it tends to fly over the riff-raff from one secured location to another (such as a helio-pad on a skyscraper).