Just wanted to say thanks to @GJM for pointing out in another thread the existing USPSA rules (Feb 2014 Edition), paragraph 2.5, that covers this situation:
2.5
Unloading/Loading Station
2.5.1
If it is possible that some competitors arriving at a range where a USPSA match is being held may be in possession of a loaded firearm on their person (e.g. law enforcement officers, persons duly authorized to carry a loaded firearm, etc.), match organizers should provide an Unloading/Loading Station to enable such competitors to safely unload their firearms prior to entering the range, and to safely load their firearms again on departure from the range. The Unloading/Loading Station should be conveniently located outside the entrance to the range (or outside the portion of the range allocated to the USPSA match), it should be clearly sign-marked and it must include a suitable impact zone.
2.5.2
Where no Unloading/Loading station is provided, a competitor who arrives at a match in possession of a loaded firearm and proceeds immediately to a match official for the express purpose of safely unloading the firearm shall not be subject to disqualification per the provisions of Rule 10.5.13.
https://www.uspsa.org/document_libra...un%20Rules.pdf
If I parse this like the retired Systems Engineer that I am, the use of the word should as opposed to shall in 2.5.1 expresses an intent but is not a Requirement. Which may explain why a marked Unloading/Station complete with suitable impact zone is not seen too regularly.
Or people shooting USPSA don't CCW.