When you have a Topo Pro with the right db-file on your gps (in map SQL), you can make a route (Where to> trails) including the Trail (or a part of the trail). Your device gives you information how to use/choose the trail. After that you can choose "Current track"on your device and then choose the tab with the mountain: you see length and elevation of the route.
Maybe it's better to start learming about Activerouting in Basecamp, see for example this video:
Code:
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Beware it's in Dutch .
Beware 2: when your gps is in the language Dutch, the Activerouting trails have the name: "Sporen".