The editing tasks will require some Python, but the rest would work fine. I think this is a great example of the kind of thing Model Builder does well, a simple batch operation.
The editing could be done using Calculate Value with something like waht is below. Pipe the Calcualte Value output as input to the next two tools in the processing chain (GPX to Feature, Point To Line) and see if you can get it work. Once you get that going, add the iterator (Iterate Files), and don't forget to use variables to name the output so it won't just overwrite one output dataset over and over again.
Expression
fix(r"%GPX file%")
Code Block
import os
import arcpy
import os
import arcpy
tmpout = os.path.join(arcpy.env.scratchFolder, "xxtemp.gpx")
def fix(gpx_file):
with open(gpx_file, "r") as f:
data = f.readlines()
data = data[:-7] + data[-3:]
with open(tmpout, "w") as f:
f.writelines(data)
return tmpout
Output data type
File
UPDATE - I took a look at your GPX file, which is an XML document. This would complicate the Python a bit -- it may be easiest to skip the Calculate Value python bit, and simply import the fake -1000000 point, and use the Select tool in your processing chaing to remove your closing point from your dataset.
UPDATE 2 - I tried the data file and it won't import with the fake last point, so I updated the script above to delete the 7th from the last line to the 4th from the last line:
<ele>-8.924316406</ele>
<time>2017-05-02T12:44:10UTC</time>
</trkpt>
<trkpt lat="57.70792238770994" lon="11.970914599637863"> ## -7
<ele>-1000000.0</ele> ## -6
<time>2017-05-02T12:44:15UTC</time> ## -5
</trkpt> ## -4
</trkseg>
</trk>
</gpx>
