I think your suggestion is very useful and I agree with you .But I have an experience want to share with you.
Once time I played with my friends.I want to test how long Ghost Mode in the end.So I store a quicksave and read the quicksave rightnow.And then I drvie into my fiend's truck and we drive as same speed .
Amazing thing happened! We drive about one minute!During the minute,our trucks still had overlapping parts and our trucks flashed all the minute.But I was bonced after one minute. I can't believe Ghost Mode can hold so long.
I think now Ghost Mode is not decidede by just seconds.It may be decided by other casual factors .But I think TMP should fix this problem.Units maybe is a good solution!