Well, yes and no. Possibly you can define the regions in ConfigurableFoldHandler, but the feature request is deeper. I would like to have the option to either hide the regions completely (not fold them, hide them - it's not the same as considering the preceding line to be the start of a fold containing the region, as I want the folding to be used only on the visible lines and not on those hidden - and don't want to see dummy folds).
ConfigurableFoldHandler is for folding only. The core needs to change in order to support hidden (not folded!) regions.