Car tie down spacing on trailer floor

I am trying to layout the spacing to install tie downs. If I mimic my old trailer that had tie down locations that worked for a Swift SE-3, those locations may not work if I ever get a newer car due to mainly wheelbase locations.

I am trying to find a compromise location that will work for old a new cars as the it appears that the most change will be in the wheelbase.

So what are you all using for the spread from the front to rear of the tire, as well as the wheelbase?

I am referencing data in the GCR in the meantime.

Thanks
Bob