Any way to keep explored areas lit using dynamic lighting?

I am about to start my first campaign using Roll20 and I was wondering if there was a way to keep the areas explored by my PCs illuminated (using dynamic lighting) when exploring, so they don't have to scribble down their own maps to keep track of where they have been?

Create an invisible png token and give it dim light out to say 60' then turn on vision and all players see light. In the token settings give all players access to it and give it an aura only you can see. Then when you put it on the object layer they will be able to see in those other corridors but shouldn't be able to see where the light is coming from. To make it harder for them to find those invisible you can make them smaller, I have had players accidentally grab the invisible lights. That's the only way to do it for now.

I think (not 100% sure anymore, and I can't test it since I don't have access to DL anymore), you can drop the invisible token on the Map Layer and it still works, that way they can't move it.

Thanks, I'll give it a try

Unfortunately, tokens on the map layer lose their sight properties while there.

What Aaron said, they would still give light but players wouldn't be able to see through them on the map layer. I know I tried.

And, before someone asks, the same happens on any layer other than the object layer.

I think the GM Layer prevents light from showing though... 

Ah, true, that's what I get for blanket statements