I've never bought an ex-fleet car before, and don't recall ever seeing listings like that on any of the usual used car sites. Would you please point me in the right direction for how to shop for these?
If you want to buy new and don't mind forking over more money than most would consider reasonable you could probably buy a brand new ford escape interceptor or tahoe ppv which is pretty much guaranteed to be as barebones and 'dumb' on the inside since they're meant to be converted to police vehicles. Don't think many dealers would order them for individuals but if you search around there's probably some out there that will.
abetterbid has listings of where local auctions are -- these are often good for that type of purchase.