I don't think the "Find Dwell Locations" tool fits your use case, as the plows would still be moving while plowing. To find the total time the plow spends on each trip through a parking lot polygon, I would use the "Detect Incidents" tool. You could either detect incidents spatially, directly against the parking lot polygons, or you could first use a "Join Features" tool earlier in the analysis than Peter showed, to enrich with the parking lot ID (with option to retain all features) - then detect incidents where there is a value for the parking lot ID. I like the second way, as it enables the parking lot ID to be carried forward onto the incidents, without requiring a second spatial join.
In either case, to get the total duration spent on each visit to a polygon, you would be looking for the IncidentDuration on the output records where IncidentStatus is 'Ended'. Or, if you want to allow for the possibility that the plow may still be in a parking lot, you could summarize to get the maximum IncidentDuration for each IncidentId.
If you want to subtract the time the plows spend stopped or parked in a parking lot, and not count that as part of the plowing time, that is where "Find Dwell Locations" might come into the analysis. I won't go into further detail on how you would use that, as I'm not sure of your exact requirements, or whether this would be relevant for you.
Depending on your desired output, "Reconstruct Tracks" might or might not be needed. It depends whether you want line features showing the vehicle's path while moving within the parking lot polygons. If you only want the start and end time for each parking lot traversal, there may be simpler ways, using tools like Summarize Attributes or Join Features against the results from "Detect Incidents".
