Dr of BBQ
I have to say I have never had anyone worry about back clearance with SS on the wall. And again there are at least two threads here that have measured the heat at grill height and at the filters and it’s just not that hot. Go to the top of the page and do a search. Every engineer wants everything to be built like a bridge.
Before you run amok and spend more time, money, and work than necessary do an internet search for a phone number or two,and talk to a company that builds food trucks. Ask them about the builds they do and then get specific and ask about your concerns with fire safety in the wall behind the grills etc.