I don’t believe anyone has installed fans or had a need to do so.
Are you experiencing problems with the device; or are you just concerned about the temperature? I couldn’t find an existing forum post / support ticket.
The 4.9 kernel has better thermal governing and will likely reduce the temperature of your device.
You should not need to use a different skin or different add-ons, but it would be good if you uploaded some logs so we can check your settings are optimal and there isn’t something causing load on your device.
I keep my Vero 4K sitting on top of my AVR sitting between a Raspberry Pi and a Dish Network Joey. Over this last summer the room it was in was over 90F for most of two or three months while it was being used. This is very much not recommended by OSMC. Despite that, I never had it overheat on me.
I understand that one can get concerned when they read about issues some people have on this site. It is important to remember that this is a support site. There will always be issues that come up for some people with most any product. Issues with heat are fairly rare outside of 4K60 playback which happens to be especially demanding on hardware.