How can I have more control of the track / camera to create a loop?
The Catmull-Rom class provided also allows you to specify control normals in addition to control points.  The control normals can be interpolated like control points in the Sample method to give you b vectors.

At any point along the track, one can fully characterise the tnb frame, as you have the t vector, the b vector is interpolated, and n = t x b.

High