It can get a little expensive but you can buy a larger hard pelican case that will accommodate more than one pistol, some will house an AR and a pistol or two. I have a 5.11 range bag that I can throw two factory pistol cases in. Depends how many pistols you have but you should be able to narrow it down to one gun case and one range bag which will sling over your shoulder. Edit: or just one range bag with the factory pistol case inside it.
Be polite, be professional, but have a plan to kill everyone you meet.
These sound like "your rules" or "club rules" not legislation. There was no mention of loaded or carried handguns in the question.
We have a large property as well..with several ranges..and guns can be freely transported between them, but should only be handled in designated areas..which are just about everywhere. You aren't required to trigger lock and hard case a gun to go from range to classroom or range to range. Maybe you are..but that doesn't mean 'reiger' is.
Not suggesting loaded and carried handguns on the skeet field is the rule of the day (no one else did either) but common sense rules are in play more than the transport regs. Our rule seems closer to Crash's..a holstered gun between ranges that allow them would likely pass..but not in the common areas. Certainly a handgun in a case of any kind can be freely transported around the facility without meeting a more stringent transport reg.
It sounds like you are on range (private) property at the time you are contemplating this. Therefore it has nothing to do with the law and everything to do with regulations at your club. You can check with the club to be sure, but it is unlikely they would allow it. I understand why you are asking, it would be handy. Now if the gun was locked and in the soft bag and the soft bag was locked in your hard gun case on the trip from your house to the range, taking the soft case out of the hard case in your trunk might be allowed. Again, club regulations rule.
Might be a club law that might only be able to un pack at the range table. Should check on that.
I know mine firing line only, but the shotgunners start unpacking in the parking lot.
If it is ON range property and does not break their rules I would see no problem.
You could use something like this. When I'm taking just one or two to the range I will use these inside my range bag. They are lockable with a padlock, as is my range bag. I picked them up from Princess Auto for $6 each.
Opaque container doesn't mean hard case. Your range bag with a lock and the daft trigger locks is good enough. Then you follow club rules like no loaded handguns while shooting sporting clays or unpacking only at the range table. Both of which are perfectly reasonable club rules. Neither are in the CC of C.