Yep there are lots of solutions here to the same basic problems.
A basic tree line should be super easy to author/tweak with appropriate working processes.
Lofting for tree-line seems hard. Personally I'd cut into the geometry the tree line will sit on (with an editable poly modifier), export that newly cut line to a new shape, then sweep/extrude that shape. Then map using the spline as a guide or UVW unwrap tools.
Then just delete the modifier off the ground object. That way you get a nice cohesive mesh that follows the terrain.
Or there are scripts that conform splines to meshes and so on.
Oodles of methods.
Or just cut into the terrain as above, then select that edge and extrude upwards (shift drag the edge)... then turn selection to faces from edges and detach etc etc...
Loft was a pain back in Max 1, it's still kinda a pain now in Max, just like NURBS it's never really been re-developed to work more logically.
In theory a great deal of the base steps of a track build could be done in one big loft element but managing the cross-sections etc is really tough!
I've tried it many times but just lost patience with the way it works on really heavy duty lofts with lots of materials etc. I've had more luck just using the very nice graphite poly modelling tool set available these days (which was completely not there back in early versions of Max making loft almost essential for the base layout to be smooth etc)
Hmmm
Dave