I just updated the code with gpx-clean.py. It can clean out bad points, but it also has functions to reduce the number of points in a GPX file drastically - a factor 30 i my test cases.
python gpx-clean.py --all input.gpx out.gpx
will usually create a much much smaller out.gpx where the lines between points covers pretty much the same area. There are arguments for reducing more or less too.
This week I have a run up to Hillsboro Wisconsin. I see that I have yet to go up there since I started with Mapillary. There are lots of Panoramio pictures showing with the straight green lines between. I look forward to maping this virgin area.
The green line map has become a major part of my trip planning.