I do not use GeoODK since GeoWidget were integrated into ODKCollect.
But in fact actually it is not possible to begin a line at the beginning of a form, complete some question loop, and end the trace at the end of the form. In other word it is not possible to create a geotrace in the backgroud of the form edition.
While this is not possible, a workaround should be to collect your tracks with an external app, and with collect :
start the form and collect route informations
loop into route sections
a. create/calculate a starting point at the begining of a section
b. collect section information
c. create/calculate a ending point at the end of a section
At the end you will have some GIS stuff to do to associate collected data to the route collected with another app.
Some discussions are going on about the Geo widgets
The possibility to collect a geotrace in the background of the form would be a great thing. In a lot of domains