denny,
I don't really know about steaming the engine in a MH, but I do know that when my son and I have taken his truck(18 wheeler) in to be washed, they do the engine as well as all the frame etc they can reach. As far as I know, he has not had any trouble with the washing. I think it would be prudent to avoid any direct spray or as much indirect spray as possible on any obvious electrical components as well as not using an extremely high pressure. I guess its using a little common sense which makes the difference. Good luck with youor problems-when you get it all sorted out and up to speed, it is really worth it.
I had a 97 Dynasty before the Beaver, and that was one of the things I noticed. The bed was right over the engine and was not insulated worth a darn. Never did fix it, just tried to stop early to let it all cool down. There's an awful lot of metal down there and it's at a pretty good temp. Wait and let it cool before you go to bed. When you're doing this, you're not in a hurry- at least I'm not.
RKP