BT747 can be used to prepare the GPX files to upload to OpenStreetMap.
To limit the time needed for the upload itself, and later for handling the upload, it is best to limit the size of the GPX file regardless of the data that you logged.
In BT747, you can select the fields that you write to the output file. On the 'Output Settings' tab of BT747, you can select the 'File Output Fields'. For OSM, the Time (UTC), Latitude, Longitude and Height fields are the minimum - you can unselect the others.
You can further limit the file size by using the filters. If you logged PDOP, HDOP, or VDOP, set their limits to 1.98 each, and if you logged 'NSAT', require at least 4 satellites.
Waypoints are useless too (for the moment) - disabling all 'Log Reason (RCR)' will disable waypoints. Generally you do not have that many, so the impact on the GPX file size will be limited.