All neons are a gray area when it comes to being legal or illegal.
Inside neons:- Are legal proving they can not distract other road users. So if you keep them out of view i.e: under the dash then they are legal. If they are somewhere like on your rof lining and can be seen out side then they are illegal.
Outside neons:- You are only suppose to see a certain light from a certain view on the car. White/yellow at front. Amber at side and red at rear. This is described as a light source so this is where you can get away with it.
This is still a grey area but if you place them so that you can not see any of the bars but only the light on the floor, then most police officers will let you pass.
They can pull you over and ask you to turn them off saying that they could be distacting other road users but you can't get done, ie fined or anything like that yet. I say yet as they are trying to change the law.
If they do ask you to turn them off just do it because if you say "no", even though theres nothing they can do about them, they could try and do you for something else.
I know this is long but should help you
"Old enough to know better, Young enough not to care"