separate track is the better idea.

most important thing is understanding rules which are not posted or wrote. playing r/c car at public place such as JITC meaning we 'must' appreciates somebody else.
a good example comes from 2 or 3 eletric player, they are always asking frequency and confirming what kind of car others use.

i think not only separate track but we need rules also. e.g. playing at separate track but on the same freq, could be disaster also.