Since we are going to interconnected, hard wired alarms, one thing that could be done is to eliminate the unit battery and have a central battery backup but that could reduce the redundency and create a situation where it only takes two failures to disable all the alarms. This may be getting better with the extended life batteries that may last the useful life of the alarm, assuming you don't have kids cooking who use the alarm as a "dinner's done" indication.
I still think these should be installed in an accessible location if they will give a reasonable level of protection. Engineering the last .00% percent of theoretical effectiveness at the cost of maintainability is short sighted.
Putting one in a tray with a fan is just stupid. Most trays aren't really big enough to get all the clerarances anyway.