There is (or at least was) a Plugin called PathCopy that I used to make copies of Groups/Components along a path.
I would create the path with lines; WELD the lines to make one continuous path; select the Group/Component, touch the Path line and then you were able to say how many copies OR the distance between them (I can’t remember which).
It is/was a Great Plugin.
If you can find it, give it a go. It’ll do exactly what you are trying to do … very quickly and easily.
Furthermore, if you have an uneven terrain, you could follow the path and then select all the new copies and basically drop them vertically so they would stop on the terrain at different elevations (following the terrain elevations).
I apologize for being a bit vague. It has been a few years since I did either of these things but I did do it regularly with SU 7.