Here's the catch 22. You can't challenge the prohibition on open carry without having standing to do so. You don't get standing without having your rights actively infringed when you try to exercise them. So basically, you have to go get yourself arrested for open carry to file a case. Your CWFL will also be revoked while you wait for it to go through the courts.
Correct, there doesn't seem to be a way to get standing to challenge the open carry ban without getting arrested first. However, if you want to get standing to challenge the concealed weapons permit requirement (without getting arrested for not having a valid permit in the first place), send in your otherwise complete permit application without a check. You will get a refusal letter and that is all you will need (I believe) to satisfy 'standing'.
This won't allow you to challenge the open carry ban directly, BUT it will allow you to challenge the licensing fee and possibly the licensing requirement itself. I believe that the absence of unregulated open-carry makes the license and fee requirement particularly vulnerable to a 2A challenge because there is no other viable option available to exercise your right to bear arms. A 'sympathetic' judge will have to either invalidate the concealed carry permit requirement or invalidate the open carry ban (either way a big win).
If you don't mind getting arrested for open carry, then I suggest open carrying an antique firearm (must be a replica or an original*). If you read the statutes closely, the ban on open carry seems to only apply to modern firearms and this may give you some legal wiggle room.
*I believe I read somewhere a court decision in Florida that concluded that black powder arms of modern design (i.e. not a replica of an antique) didn't qualify as antiques (Florida has a different definition than the Federal definition of antique arms).
I think that the legislative approach is the best approach, however.