These are apparently called "leader lights", and they indicate that the car is currently in the top three in its class. If you have one leader light on, you're currently 1st in your class; two leader lights means you're 2nd; three means you're 3rd; and if they're all off, that means you're 4th or below.
As an example, you can see in your screenshot ...
I think you have a minor issue with physics here. It's not 100% clear to me what you're describing, but there are two ways you could 'harden' the shoe:
A solid mass between the upper and the foot (imagine, say, a roll of coins)
This would hurt. A lot. Brass knuckles do hurt the fingers that wear them when not braced properly, and I doubt you could brace ...
Use this to visualize it. You need more space to make shots against the rail, even for a 7-foot (bar size) pool table. If it's just for fun or if you have shorter pool cues, you might be able to get by. Ideally, you should have 40% extra room for a standard 4.9' pool cue for stroking, which would require an extra 6.9' offset on each side of the pool table,...
The NSD swim was the product category I was looking for.
It is capable of calculating the force exerted and the distance during a swim.