He's such a sweetie! Sounds like he's going to be a really great dog for you. Not that I'm biased or anything!
The only thing I do want to point out is really think about the "snarl" idea, for several reasons. One is that bystanders who see you seizing with a snarling dog over you may be more likely to call a police or ambulance because they don't feel safe approaching. The second is that police can and will act with deadly force if they think an 'aggressive' dog is preventing them from getting to you in a presumed medical emergency, either in a situation where they happen to be nearby or if someone calls them in. Then there's the image - service dog handlers already face a lot of scrutiny from the public, because they don't "look" blind/disabled, because their dog is the "wrong" breed, because it's not from a program, because they've heard about "fakers" and think they're being allies to the disabled by being suspicious of every dog with a vest or SD harness. By training a service dog to do a behavior that can be read by the non dog-savvy public as "aggressive", you could be leaving people with the impression that service dogs are aggressive, or potentially dangerous. That could work towards making your life and the life of other SD handlers more difficult.
You might want to look into body block or cover training instead, where the dog passively puts themselves between you and anyone nearby, or having him retrieve a card of some kind that explains you're epileptic and please don't call the ambulance unless XYZ (it goes on too long, you've hit your head, etc.).
The only thing I do want to point out is really think about the "snarl" idea, for several reasons. One is that bystanders who see you seizing with a snarling dog over you may be more likely to call a police or ambulance because they don't feel safe approaching. The second is that police can and will act with deadly force if they think an 'aggressive' dog is preventing them from getting to you in a presumed medical emergency, either in a situation where they happen to be nearby or if someone calls them in. Then there's the image - service dog handlers already face a lot of scrutiny from the public, because they don't "look" blind/disabled, because their dog is the "wrong" breed, because it's not from a program, because they've heard about "fakers" and think they're being allies to the disabled by being suspicious of every dog with a vest or SD harness. By training a service dog to do a behavior that can be read by the non dog-savvy public as "aggressive", you could be leaving people with the impression that service dogs are aggressive, or potentially dangerous. That could work towards making your life and the life of other SD handlers more difficult.
You might want to look into body block or cover training instead, where the dog passively puts themselves between you and anyone nearby, or having him retrieve a card of some kind that explains you're epileptic and please don't call the ambulance unless XYZ (it goes on too long, you've hit your head, etc.).