I'm wondering whether regular aerobic exercise would have any affect on decreasing the amount of time PeTH would be detectable in the blood samples used in testing

NO... don't drink and you will have no problem passing any tests.

I have not found any indication that ^ exercise will "cleans the blood cells out any faster" essentially, which is what you are asking. Someone here inquired about donating blood to speed up the process as well, and I can't find any answers suggesting that would do the trick, either (unless you drain your entire body and refill it, perhaps). PeTH seems to be one that neither water consumption, nor any other documented ways will speed up the processing out of the body. There also seems to be a fairly high degree of dispute/uncertainty about PeTH testing and time frames that it is detectable & amount consumed.

Again - I'm not a Dr. nor a professional in the medical field, just a researcher and recovering alcoholic.