Looking for techniques to model resistance to roll rotation in a very simple, force-based flight model
The way this is commonly done in simulators is using linearized stability derivatives. For your example, one could calculate the rolling moment on the aircraft as the sum of such terms as:  rolling moment due to aileron deflection angle, rolling moment due to roll rate (roll damping), roll moment due to side slip angle, roll moment due to yaw rate, roll moment due to rudder.  For doing simulation each of these coefficients can be precalculated based on flight testing or CFD and then during simulation lookup tables can be used to find the current value.
My suggestion is that you take a look at JSBSim which is a cross platform opensource flight dynamics model that is used by FlightGear for example.  JSBSim allows one to build an aircraft model by defining the values in an XML file.  The website includes documentation, some links to papers and books, and example aircraft that are very useful.