Wyoming Snowmobile trails - Garmin Montana

Looking for help to get the snowmobile trail maps for snowies and togwotee onto my Garmin Montana. I found a file on snowest that someone posted (kmz file type) that has them all and I got it imported into the Garmin basecamp application - they basically came in as all separate tracks for each trail name. I then color coded all of the trails to match the normal paper maps. When you go to upload it to the garmin, the files come in as tracks and they will not show up on the normal map. I then merged all of the files into one file by exporting them out as a gpx file. When I brought them back in, its the same issue. I basically want them overlayed onto the garmin Montana main map so they are there all the time. I've seen several postings online for this but nothing clearly explains the process. It seems like they all resort to converting the gpx file to a jpg file using a 3rd party software but nothing explains the whole process clearly. I am leaving next weekend and am hoping to have this figured out by then.

Thanks! Seemed to work ok on the Togwotee maps I found. Image isn't the greatest once you overlay it on the topo and satellite imagery but should be good enough for my trip this weekend until I find something better.