Bill,
It would be helpful to know what city/state you are located in, but the general answer is that RH in the 20%s is not ideal. Most assuredly the RH will fall much more when you reach the lower temperatures in the winter. I would imagine it even could fall into the single digits if you are in the northern tier and probably into the teens if you are in the middle tier. The colder the outside air, the lower it will fall.
You have not said if the paintings are on canvass or on wooden panels, but it really does not matter that much. Both will not do so well at lower RH levels, but the ones on canvas will respond to changes of RH much faster, with some potential for more damage.
The imperfect solution is to keep the temperatures during the day lower. That would cause the RH to rise. You can see this already when you lower the nighttime temperature. Just have people wear sweaters. Again, dependent upon where you are located, this may not be good enough in the colder weather, so you will have to decide if the elevated risk of damage to the paintings is worth displaying them in the room. The more perfect solution probably is too expensive and may risk damage to your building, so imperfect or another location with better conditions probably are your best alternatives.