The other attorney did a thoughtful analysis -- and might be correct -- but to do so he's asking for a "test case" -- because in today's environment -- if a police officer finds you with a firearm on your person in a vehicle on school grounds -- CWP notwithstanding -- I think you're in for a problem.
If you're wondering why -- here's my analysis: Florida law under 790.06(12) does not exclude carry on school "grounds" but does at a school "facility" or administration building. Since "facility" is not defined, it leaves this as a "grey area" -- and you might be a "test case" on whether a "facility" includes school driveways. Since most schools are fenced -- the fenced area stands a good chance of meeting the definition -- although a good faith argument could be made the other way around. Still -- who wants to be a "test case"?
Likewise, Florida Statute 790.115 fully covers what you can or can't do on school "property" -- which language would definitely include school "grounds". That section only allows possession of a handgun in a vehicle "pursuant to 790.25(5) -- which requires all handguns to be "securely encased". There is no exception for a CWP. There can also be additional exclusions.
So -- while there are many arguments that can be made -- all in good faith -- my opinion is that the only "safe" way to carry in a vehicle -- is securely encased. I'm not saying that's the only way it would be lawful. I'm just saying that's the only "safe" way for it to be lawful. Everything else would depend on the eventual "test case" outcome.
Of course, if you want to give it a try, and can fork over ten grand for my fee, plus a few hundred more for your bond -- please let me know.