Food truck/trailer. Handling hot coals

Hi there, I'm thinking about building a bbq business out of a concession trailer to offer the good people of New Zealand low and slow bbq straight from the smoker and over the coals. Outside of complying with local fire/health department regulations, when it is time to pack up and move on, what are the practical steps you can take to putting out the fire in your smoker/pit/grill while out and about at an event or kerb side. And what do you do with the ash, left over charcoal?

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!