I think its a good idea and you should pursue it. You're thinking of trucks like these?
https://www.google.com/s...mp;biw=1180&bih=883
I think you can probably corner areas like Upper Hill where there are many office buildings but few eateries. I remember I worked on Mombasa road in one of those buildings along the highway a while back. There was no food shop within the building, but an enterprising lady with a car would come everyday with cooked food to serve the people in the building.
She would park her car at the basement and would basically serve food from the boot. She probably had at least 50 customers on a bad day. She also likely didn't have to deal with kanjo having such a niche market that was out of the way.
I once toyed with the idea of bringing in a New York style hotdog stand, but didn't have the money at the time.