I just wanted to add how my overtray was working to give you guys an idea in case you thought of getting one.
This thing works great for any kind of debris! snow, gravel, dirt, etc don't stand a chance. Only a couple drops of water were in the chassis after running a full battery through LOTS of snow (the whole truck was caked, but the chassis was good). I have it velcroed with the supplied velcro (2 little strips), plus two little dots of velcro that I got from walmart for $2. Let me say, the velcro works great and has not come loose yet.
The material is a little thin, but it does the job and doesn't really take any hits when flipping since the body does that, so I'm not worried about it breaking.
Heat wise, this made my motor definitely run warmer than usual. The temps were about 30 degrees hotter than without the overtray after about 10 minutes. However, I don't have all the vent holes on the top open, so with those cut open and maybe a heatsink/fan temps may be better. If I'm just doing street runs I don't use it so I get more airflow.
Overall, great buy if you run in lots of mud and snow but make sure to check your temps and do appropriate measures to keep the heat down. If you have any questions post em!
Here's a few pics...