Well with things like these, it's best to either have some sort of hard object like a destk or something metal that will absorb the heat and act as a heat sink.
80 degrees Celsius isn't "that" hot so you shouldn't have a problem running the cpu at that that temperature. In terms of comfort for you, if you have one laying around you could get a skinny, hard backed book laying around the house or something of that nature and sit it on your lap.
No matter how much ventilation you have, the MB will always heat up, that's the result of the processors and other internals causing heat when put under stress. Unless the temperature in the room is somewhat low (and I mean around 70 F) it's going to stay hot.