Hi Jacasteel,
I would recommend the GPX method for routes with over 20 waypoints. Try exporting your 42 waypoints to a GPX file. Then copy the exported GPX file to the GPX folder on your Nuvi. Unplug your Nuvi and when it restarts - you're done.
This is much faster, requires no internet connection, involves no other software and has no waypoint limits other than possible those imposed by the Nuvi.
Welcome to the forum by the way!