Hi StirCrazy,
The moisture meter is a whole post topic by itself, and your quest for more info on it has inspired me to create a post about it here on the new GS forum. 🙂 The stand alone post is in the works, now, but it will take me some time to finish. Maybe a week etc with what I have going on right now. But it will come as there are a lot of folks who can benefit from knowing about a moisture meter and how to use it on there camper. I'll give you the cliff notes version here, as this can help JK1.
See this post on the Sunline Owners Club forum where I first started using a moisture meter. https://www.sunlineclub.com/forums/f71/moisture-meters-for-inspecting-a-camper-17613.html
That post from 2017 was the start of my using the meter and all it can do to find leaks you cannot see or smell. Over the last seven years I have used it a lot on many campers to find moisture that you cannot see. Many owners who's camper in looked at with it was shocked and they could not see any water signs in the living space. And when we opened up the camper, it was wet.
That Sunline post may hold you over until I get the Good Sam updated post up. As a perk, Lowes right now is clearanceing the model I use, not sure why but they will not be this cheap again for the level of feature that specific meter can do. https://www.lowes.com/pd/General-Tools-Instruments-Digital-Test-Meter/50284821 On the General Instrument web site that model is still for sale. It may be at Lowes they now offers a Kobolt meter, their brand and no longer want to offer the higher end featured one I use. You may have to order it online if the local store of out of them. I just bought 2 more, a spare for me and one for my son for his camper. Anyone owning camper ideally has one if you plan to keep a camper a long time. Sooner or later you will need to use it.
Hope this helps,
John