I went ahead and did it! I picked up shelving from IKEA and went through with my 'catwalk' project this weekend
Newton, being the adventurous kitten that he is, immediately started exploring the new territory - although I had to help him out a little bit to figure out the sequence of which platforms to jump to (I'm sure he would've been fine on his own, but I was a bit impatient). His mom Newt hasn't tried it out yet - it sometimes takes her awhile to try new things.
Here he is lounging in his new spot, and playing hide and seek with his favourite toy mouse.
I put non-slip tape on the shelving, making sure to put lots on the climbing platforms leading to the top shelves.