Space between saddle bag and rear tyre

[Gim300]

Hey folks,
Just trying to put together my bikepacking kit for my first adventure but having some difficulty due to my small bike.
Once the saddle bag is fitted, how much space should be left between it and the rear tyre? It would only ever be on a hardtail so no need to take into account suspension.
Would ideally like to run a 14L rear bag but not sure if I can get away with it?
Cheers