We have the axle peep holes also. We might get rain that morning so they may hold the race at the Marriott Hotel
We're using the metal tape on the bottom and I poked open the peep holes and was going to run that way and also thought to add a few pieces to cover after the check them.
You should cover it up before the check in, so you know your weight, and just quickly remove/put it back if they ask for it. Also if they weight the car first, you are not allowed to add anything to the car later.
Personally I find that rule weird, and the first time I see that as a rule. It's normally given as advice if you want to glue your axles in. I feel drilling those holes can compromise car strength and maybe even make the axle less secure. I wish they pay more attention to wheels which fall outside the specs (too light ect. and if the car runs on graphite and not oil.