Sacramento Zoo keeps RRH's and Bongo mixed, as far as I know.
Beardsley Zoo's current peccary exhibit is very lush in the summmer. When they get their new exhibit, I'm not quite sure if they'll be sharing it with anteaters, or if they'll be seperated.
San Diego Safari Park - warthog and bat eared fox.
Caldwell Zoo - warthog in large field savanna with zebra, impala, ostrich, kudu. (The field is so large that the pigs do NOT destroy the vegetation, so maybe size is the key?).