Servals and asian golden cats use enclosures of chimps and orangutans, respectively, at night (in rotation with apes). I saw it online in one zoo in Asia or South America, cannot find now which one.
Fennec foxes with trumpeter hornbills - Augsburg. Fennecs could be good in mixed exhibits with animals larger than themselves.
Yellow mongoose with vultures and secretarbirds in a walk-though aviary - Magdeburg. Is this the first walk-through enclosure with carnivores of any kind?
Would meerkats be suitable to a walk-through exhibit? Prairie dogs are exhibited this way in Rotterdam, and visitors somehow can resist touching them. Meerkats bite, of course, but probably no more than any rodent of similar size.