So I have noticed a few people have extended their elevator and rudders. I am at a point where I could do this before I cover them. I have a few questions before I do though. My plane is a KF3

1. I'm under the impression this mod would improve low speed control authority. Are there any other benefits/downsides. Does this put any more stress on the air frame that I should be concerned with?

2. How much should I extend them? My first thoughts were to measure a new model and make mine similar.

3. Material? 4130 Normalized?

I would love to see some pictures and here others general thoughts on this.
Thanks