I think the best way to get file output such as an exported plot is in your code, not using BehaviorSpace.
For example, if you want to export a plot at the end of each simulation, add something like this to the code that stops the model in your go procedure.
if ticks > 100 [ ; for example if your model stops after 100 ticks
[
let plot-file-name (word behaviorspace-run-number "plot-export.csv")
export-plot "results-plot" plot-file-name
stop
]
This creates a separate file for each model run in a BehaviorSpace run.