We employ a surface flux transport (SFT) model in order to simulate the detailed magnetic structure and dynamics of exoplanet host star photospheres. In coupling the SFT model with a potential-field source surface (PFSS) extrapolation of coronal field, and with a suite of forward-modeling tools for the derivation of coronal X-ray and EUV emission, we simulate self-consistently the magnetic structure and energetic budget of host star surfaces and coronae. In particular, our modeling framework can be used to determine magnetic field structure and plasma emission of a host star with finely-gridded 3-dimensional spatial information as well as complete temporal coverage over stellar cycle timescales. In order to constrain exoplanet space physics environments with an eye toward questions of habitability, we examine the relation between host star X-ray and EUV emission and planetary ionospheric response. We employ a relation between stellar emission input to the planetary environment and changes in ionospheric conductance, Joule heating, and the resulting radio emission. We aim to explore the conditions of star-planet interaction that might lead to observable radio signatures of exoplanet ionospheric activity. Radio emission signatures from exoplanet systems, if found, would contribute greatly to our understanding of the ionospheric and magnetospheric behavior of planets outside of our Solar System.