Ok, this may seem goofy but there was a reason behind the madness. I attached a highly reflective CA plate to my RC10 GT remote control car and tested the range that I could get a speed reading on the small target. I did this with the plate and then with the plate covered with a Lexan cover with IR/UV absorbing film.
With just the plate it averaged 120-130 feet away. With the plate and cover it averaged 90-100 feet away. I was hoping for better, but heck, at least the home made cover does cut down a little. Although the furthest distance measured was 153 feet with or without the cover, the speed acquisition distance was shorter more often when the cover was used by about 20%.
Not sure this really has much value other than to show you don't need much of a target to get a speed reading. In this case, up to 153 feet away with only about 1/2 square foot of surface area gets a speed reading.
I'll have to try the PLII against some of my remote control airplanes next time I go flying to check out their speed!