Looking for Guidance on Vehicle management

I would approach this in a two-step process.

The ultimate goal which will be the second step will be to  create a saved table to table import which will import vehicle records into the scheduled service tasks table for all vehicles that are now due to have a task created. Then that save table to table import can be run every night and any vehicle needing a task created will get it created.

But what I would work on before that is to get that working on a report and have a single flag field on the vehicle record to filter the report. I have found in the past of buggy behavior in save table to table imports when you try to get too fancy with the filters. So I have often found that a  set of filter which should be perfectly valid doesn't work in the same table to table import and I've had to reduce it to a single checkbox field.

 OK, so now we got to figure out which vehicles need service. Arguably that is simple. Create a formula field on the vehicle record which will calculate to the rounded 5000 km below the vehicles current mileage. So for example if the mileage was 25,500,  The calculation would result in 25,000. 

 Then there would be a trial table of scheduled tasks and it would record that the service now due is the 25,000 checkup.  Now you can compare the highest scheduled checkup with the 25,000 calculated in the vehicle and see that the service test had already been created.

but then the vehicle hits 30,100 so the flag field would now be true because 30,000 is greater than the scheduled 25,000 mile service task.

so that night the Automation would run the saved table to table import and one record would be created.