I've seen a couple backwoods inside enclosed trailers during my google trawling with chimneys up through the roof or under extractors. But I do agree it looks a lot safer working from a deck or ramp, even for lighting starter chimneys.
In New Zealand we don't really have a daily food truck scene and do not operate out of commissaries. So I'd like to include everything I need for prep and cooking on board the trailer to avoid the high price of renting or establishing an offsite registered kitchen. And I want to stay true to the charcoal experience of cooking - but safety and practicality first!