Obviously,any manufacturer is going to put that liability disclaimer in there. However,I will add it is not totally invalid. If I am parking to run the gen,I park where the air/wind will carry the exhaust away. Also,if it is not blistering hot,I run it long enough at night to blast the A/C,cool the unit down,and then shut down.Usually works.Especially at night when the sun is not heating up the coach. Also,I have made a small extention for the gen exhaust to carry it further away.Of course,I only use it when parked.
Be careful with this.You dont want to force the gen. to push the exhaust too far out the pipe,or you will run into new problems. A foot to 18" seems to suffice. (as with thor,this is a liability statement. I claim no responsibility if you extend your gen. exhaust,and something goes wrong!)
Having said all that,I have used the gen all night while asleep,and no issues.
Happy Trails