As is well known, "camp" in Latin is castra, neuter plural decl2. This also means "forts" and is often found referring to Roman army camps.
(1) Is it the only word usable when referring to a few travellers making an ordinary unfortified night camp?
(2) In postclassical and mediaeval Latin, how often is the wrong form castram, castrae found? Some people have likely made that mistake, because castra got into the Anglo-Saxon language as sēo ceaster = "the (Roman) town", feminine singular, from which "-chester" and similar at the ends of some English placenames.