TomTom's trip file is called an ITN. A GPX can be translated into a ITN with sofware (free or donation) called GPSbabelGUI (search the web). It does support a large number of stops. The ITN file is a text file. In it, you will see Longitude, Latitude, Name, and a digit, 0-4. You can use notepad to open the file, and find/replace to change all the zeros to the appropriate number.
0 is a waypoint
4 is a start point
2 is a destination/finish or stopover
This is what the file will look like after it is converted to an ITN
10471502|4459027|Devils Tower National Monument|0
-10382907|4372941|Jewel Cave National Monument|0
Assuming you don't have a starting point, you will not need to change any entries to a 4. All your stops should be 2's (instead of zeros). The dividing line between fields is the shift of the backslash key. It is sorta like a colon, but the two dots are vertical lines, often referred to as a pipe. Look for it on your keyboard. I think you can have as many as 59 "stops" or waypoints in your file. TomTom navigates TO stops and THROUGH waypoints. It will give status -- distance to, arrival time, etc. to the next STOP, and change to the next one as you get to the former one. Sometimes it doesn't, and you have to go to the Itinerary file, and set your next stop as the one you want to go to. Depends on how close the point on the map is to where your GPS is as you arrive. Not all TomToms are created equal, I use a TomTom 300, actually several, so I can't speak for other models. I think the TomTom One will not do Itineraries at all, check the manual. After you reach your Stops, the GPS changes the last digit to a 3 or a 1, meaning it has been visited. But you don't need to do anyting. There is a ITN directory on the TomTom GPS that you can see if you attach a cable to it, or put the SD card into the appropriate slot on you computer. That is where you copy your ITN file. It would probably be easier to name all your ITN files the same, and start them with the letter A so they float to the top of the list, when you try to "load" it from the TomTom menu. I assume you don't need yesterdays file today or in the future.