BaseCamp uses a .GPX format. Files need to be in .gpx for uploading
I have tried several sites that offer format conversion but I prefer:
Conversion from a GPS format to another GPS format
I download many sets of Waypoints (WP) from Discovery Owners at :
https://www.discoveryowners.com/test.asp and convert the WPs into the format needed to upload into BaseCamp, where they are stored and uploaded to my GPS as needed. Groups include: COEs, Casinos, Elks Lodges, PassPort America (which is outdated), Days End, Hot Springs, Slot Canyons, Dump Stations, Rock Hounding areas, Western Mine’s, and maybe a couple others. As I change locations in the motor home the closest ones show up first. Just go to the Garmin Saved folder to find them.
I don’t load all of the above on my GPS at the same time. Just the ones near my route. Instead they are all loaded in BaseCamp and I load the area that I will be traveling in during the following month. I have thousands of wps stored in BaseCamp. A few months ago I purchased (on line) wps of all the mines in the western US. This was thousands alone.
I do my route planning on BaseCamp, selecting waypoints on the highway from Google Earth, often right after a city and if I have a specific way I wish to go through a city I select waypoints within the city on the route. When creating a route I number the waypoints (1, 2, 3, …) then if I need to add one I use as decimal such as 1.1, 1.2, 1.3 Numbering is for my benefit when creating the route. I save used routes and download them from my Garmin back into BaseCamp. I prefer to choose my route from Google Earth then copy and paste the coordinates into BaseCamp.
I too found BaseCamp challenging, but when I saw the possibilities, I knew I could learn it. I have been using it for several years. I looked into other GPS companies but could not find others with applications for thier gps products.