we've got intermittent rub/squeak also.....from the very large TV stuffed in the center overhead. On smooth roads it is silent, but depending on temperature and road, it will work up a bit of noise. I struggled to stuff in a couple soft shims under the bottom corners, which 'helped' but didn't cure the problem. Will have to study further.
Made the kitchen quiet.....had a roll of surplus 1/8" foam sheet....stuffed a layer between each of the offenders---worked great!
Also found the bath blind has to be clipped down into brackets or it rattles.
Leaving Thursday on new voyage; likely to find new things to hunt down....