I have played around with them, but never put one in a model.   I am pretty sure that they won't be hard to light block.  

They have a purplish color to them, and you would have this flooded in the cock pit, but I think this is a good idea.

I have not used the Tamyia putty, but Squadron I have used.  Not a fan of it.  I use to be then I found bondo spot putty at an automotive store and now I won't use anything else.