Thanks so far... today I removed some of the cab trim, specifically that that wraps the edge of the cabover bed. After removing the trim I could now see into the areas where the cabover frame adjoins the house. There was more than adequate felt like material between the two surfaces, so no worries there.
However,the plastic trim pieces that cover and wrap the edge of the cabover bed are able to rub against each other and against the adjoining cabinets. I found that by giving them a twist or a nudge I was getting squeaking noises.
It was easy enough to fix lengths of felt on all touching surfaces and now there is no plastic to plastic or plastic to timber contact.
One can only hope that this solves the squeaking noises we were experiencing.