Mixed information.
Hi. First off, start by taking into consideration the humidity for your area. Many of the people here are in Florida. People in Florida have generally posted that humifity is not that important unless you have a bad shed (no flames, it just an observation). That because in Florida they dont have to worry about humidity. In New Mexico (here) if I dont add moisture, the humidity in the vivs is about 10% sometimes. I try to keep the humidity at least near the 40% range just so their humidity doesnt bounce from 10% normal to 55% when they are shedding and then back again post shed.
Another thing to consider is how you heat the viv. If you use a heat lamp then it will be tough to keep your humidity in the 40 to 55% range. If you use an Under Tank Heater (UTH) it will be easier to keep humidity in the tank.
Moss or paper towels in the hides will work fine. To help maintain a reasonable humidity in the whole tank we wet a rag and lay it across part of the screen top of the viv. OUR humidity gauges are near the lower corner of the vivs opposite from the heat source. Cant say that is the right place, but thats what we do. A good thing about the wet rag method is you have ways to vary the humidity. You can make the rag more or less wet, cover more or less of the viv,..
By the way, very good job doing your research, setting up the viv in advance and making sure its right!!
Hope this helps.
Jimmy