In reply to Marek:
> Virtually every GPX generator produces a different XML structure and they are not necessarily cross compatible.
There is an XML schema for GPX files. I've not experienced too much problem with interchanging between different tools, or manipulating them with simple parsing scripts, or even creating my own GPX files from other coordinate pair sets.
The WheresThePath website is still just about working, even though my colleague Bill discontinued supporting it due to Google mucking about with tile limits. It has a 'magic wand' that can be used when creating routes, which uses publicly-available PRoW routes segments (where the LA has published them). This makes creating routes fairly easy.
Alternatively, pretty much any mapping app will allow route creation; you don't need it to be a perfect track, so create as many route segments as you need to be happy with the route fit to the paths. Routes will not have time data, obviously. Depending on the tool, the route may have elevation data.
Post edited at 23:16