" where to find the rollout that you've posted a screenshot of?"
My apologies, I pasted a wrong image (it's fixed).
In my opinion, your approach would be the recommendable way - build the RC object based on "section splines" of such surface. Having lines closer might work better in this case - I've used the SectionSKAN script
in the attached scene to get them easily. To get more items, negative Padding
values can be used. Attaching modified scene. Hope that helps a bit.
Another possible approach might be to use the work-flow described in this thread
or using the Forest Pack plug-in in the UV mode, might be a possible option too.