Where did you hear such a silly thing? Snakes don't blink because they do not have eyelids so things don't get into their eye. They burrow through plenty of things stronger and rougher than aspen without issue. This fear is just silly.
As for layering paper towels to control the uth I don't see how you have a forum full of great information and thought that was the way to do it.
Why not just get a tstat like you are supposed to?
A dimmer will work but its not the best method. A dimmer is dumb, meaning it does not know what the room temp is doing and delivers the same amount of power regardless of the room temp. This means as the room gets colder the uth gets colder and if the room gets warmer the uth gets warmer. A tstat works with the temp and adjust the power accordingly so the uth stays at the ideal temp.
Get a good tstat and be done with it.
Note: Tstats at most pet stores are junk. Search the forum and read/learn your options and buy what is best for you. Buy the best you can as it is the most important thing you can buy for your snake.