Wow - the money and time spent coming up with that and you decided not to go with a small Weterbeke or something??
Let me guess - you'll trust your life on a $35 CO2 detector? Your basically placing all the gas fumes, CO2, in a sealed tub - with no USCG spark protection whatsoever..... and you plan on sleeping in that thing?
You do what you want - but I'll say a prayer for you if you keep that set up. That's one of the most dangerous set ups I've seen.
Think about it - if it was that easy to use a portable generator in the engine room - wouldn't everyone be doing it?
I'm going to beg you to get that thing out of the engine room before something happens.