Hey fellow 808er!
I think this is an intriguing and creative idea, but will probably take some more research and maybe even experimentation. I know for a fact similar things have certainly been done (probably extensively in the past), but hazy on the specifics.
It can be hard to get chickens to try eating something so new and exotic even if it is wholesome. Some find it to be more trouble than its worth. Old sources I've read warn about feeding raw meat of any sort to chickens because it may encourage cannibalism, and it also poses more disease risk, so i think cooking makes sense. Some people say chickens can be reluctant to eat things with hair on them too. Some people might feed the carcass to grubs or maggots to convert it into a more convenient and palatable feed with less hassle (all chickens LOVE grubs and maggots), but you have to be aware of how to avoid botulism. I would also suggest caution in general regarding what the mongoose may have been eating or getting into...
I would put in a word against drowning as a killing method. Evidence suggests it is not a very humane way to go. a quick kill would be preferable--perhaps something like a quick thrust to the head with a hawaiian sling fishing spear or some other quick and overkill trauma to the head (don't use lead pellets or bullets because you def don't want to risk chickens swallowing lead, and besides, we hardly need more lead polution around these days, anyway!)?
