This is a complex question. Short answer - it changes.
Dew Point is the temperature at which atmospheric moisture will condense on a surface. This is NOT impacted by air temperature.
Relative Humidity is the ratio of current atmospheric moisture level to dew point AT A GIVEN (current air) TEMPERATURE.
On a nice, calm day, DP will change very little. RH will increase significantly at night (cool) and decrease significantly during the heat of the day.
In the winter with cold windows, an indoor relative humidity of 40% will often be above the window dew point (condensation occurs). In the summer, even 80 or 90% RH will not condense because it is hot outside.
The window condensation test is a good measure of when humidity is too high. Normally, windows are the least insulated, therefore coldest surface in your RV. If water does not condense on windows, it is unlikely condensing anywhere else.
If the windows are collecting condensation, which may then run down into the walls and cause damage, other surfaces may be doing the same thing. Humidity is too high.
Dry air is sometimes hard on the throat and lungs. It dries them out.
So, there is no simple answer. I hope this helps.