10forty2...I have the exact model and color as yours in a 2000 model.
I also use the Genturi overnight on occasion. I have always used a second portable battery powered monitor on the counter top in the bedroom as an extra precaution. Also replaced the hard wired unit last year as well. Never had any issues with all vents and windows closed.
I use a couple of the round suction cups from Harbor Freight to support the Genturi straps. The cups have a handle that pulls good suction. They work best with a few drops of water on the rubber surface as you apply the suction. I didn't want to drill holes in the fiberglass.