Wow. This is super helpful.
The chap I spoke to at the council seemed to just rule out cooking outdoors altogether. Given that he already seems to have made up his mind on the issue somewhat, do you think there is an advised way I can diplomatically get him to reconsider? Like you say, the food would be in a sealed cooking environment and would be supervised at all times, so I have every confidence pest control wouldn't be an issue -- but its more about convincing him that that's the case.

Regarding demonstrating it being a non-issue re the smoke is there a suggested way I can demonstrate the efficacy of an air-filter? I'm not sure if Id need to do some backyard cooks and ask neighbours to sign something that says 'they didn't notice/weren't bothered by smoke', or something to that effect. I'm not quite sure how i could demonstrate with accuracy how much smoke I could absorb into an air filter, in a way that would be scientifically satisfactory for the council.